The effect of contamination on selected physical and chemical characteristics of mineral trioxide aggregate

Aim: To evaluate the effect of various environmental (clinical) conditions on the physical and chemical characteristics of Mineral Trioxide Aggregate (MTA). Methodology: Initially preparation of specimens was standardised. Moreover, a novel mixing technique, trituration of encapsulated MTA, was developed. The effects of acid and blood contamination on various characteristics of MTA including compressive strength, surface microhardness, push-out bond strength and total porosity were then evaluated. Furthermore, by using X-ray diffraction analysis the hydration process of blood contaminated MTA was studied. In addition, the microstructure of contaminated MTA specimens was compared with control groups. Results: Methods of mixing and placing MTA significantly affected the hydration process and consequently the physical properties of the material. The lowest and greatest compressive strength, Vickers surface microhardness, and push-out strength values of MTA were found after exposure to pH levels of 4.4 and 7.4, respectively. In addition, scanning electron microscopy revealed a lack of needle-like crystals when the material was in contact with more acidic solutions. The hydration state of specimens partially mixed with blood was more complete than those mixed entirely with blood and less than specimens that were hydrated only with water. Conclusion: In experimental investigations, use of controlled mixing and placement techniques when using MTA is essential in order to standardise specimen preparation. Delaying the placement of the final coronal restoration in clinical situations when MTA is contaminated is recommended so that the material can acquire sufficient physical properties to withstand the acid-etch procedure and the condensation pressures that occur during the placement of a restoration and/or produced through indirect masticatory forces.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The effect of contamination on selected physical and chemical characteristics of mineral trioxide aggregate

Summary Aim: To evaluate the effect of various environmental (clinical) conditions on the physical and chemical characteristics of Mineral Trioxide Aggregate (MTA). Methodology: Initially preparation of specimens was standardised. Moreover, a novel mixing technique, trituration of encapsulated MTA, was developed. The effects of acid and blood contamination on various characteristics of MTA including compressive strength, surface microhardness, push-out bond strength and total porosity were then evaluated. Furthermore, by using X-ray diffraction analysis the hydration process of blood contaminated MTA was studied. In addition, the microstructure of contaminated MTA specimens was compared with control groups. Results: Methods of mixing and placing MTA significantly affected the hydration process and consequently the physical properties of the material. The lowest and greatest compressive strength, Vickers surface microhardness, and push-out strength values of MTA were found after exposure to pH levels of 4.4 and 7.4, respectively. In addition, scanning electron microscopy revealed a lack of needle-like crystals when the material was in contact with more acidic solutions. The hydration state of specimens partially mixed with blood was more complete than those mixed entirely with blood and less than specimens that were hydrated only with water. Conclusion: In experimental investigations, use of controlled mixing and placement techniques when using MTA is essential in order to standardise specimen preparation. Delaying the placement of the final coronal restoration in clinical situations when MTA is contaminated is recommended so that the material can acquire sufficient physical properties to withstand the acid-etch procedure and the condensation pressures that occur during the placement of a restoration and/or produced through indirect masticatory forces

Isolation and differentiation of adipose-derived stem cells into odontoblast-like cells: a preliminary in vitro study

Objective The aim of present study was to isolate and differentiate human adipose-derived stem cells (ASCs) into odontoblast-like cells. Materials and Methods In this experimental study, human adipose tissues were taken from the buccal fat pad of three individuals (mean age: 24.6 ± 2.1 years). The tissues were transferred to a laboratory in a sterile culture medium, divided into small pieces and digested by collagenase I (2 mg/mL, 60-90 minutes). ASCs were isolated by passing the cell suspension through cell strainers (70 and 40 µm), followed by incubation at 37ºC and 5% CO2in Dulbecco’s modified eagle medium (DMEM) supplemented with fetal bovine serum (FBS 5%) and penicillin/streptomycin (P/S). After three passages, the ASCs were harvested. Subsequently, flow cytometry and reverse transcriptase polymerase chain reaction (RT-PCR) were used to detect expression levels of NANOG and OCT4 to evaluate stemness. Then, a differentiation medium that included high-glucose DMEM supplemented with 10% FBS, dexamethasone (10 nM), sodium β-glycerophosphate (5 mM) and ascorbic acid (100 µM) was added. The cells were cultivated for four weeks, and the odontogenic medium was changed every two days. Cell differentiation was evaluated with Alizarin red staining and expressions of collagen I (COL1A1), dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP1). Results The ASCs were effectively and easily isolated. They were negative for CD45 and positive for the CD105 and CD73 markers. The ASCs expressed OCT4 and NANOG. Differentiated cells highly expressed DSPP, COL1A1 and DMP1. Alizarin red staining revealed a positive reaction for calcium deposition. Conclusion ASCs were isolated successfully in high numbers from the buccal fat pad of human volunteers and were differentiated into odontoblast-like cells. These ASCs could be considered a new source of cells for use in regenerative endodontic treatments

The Micro-Shear Bond Strength of Various Resinous Restorative Materials to Aged Biodentine

Introduction: The type of materials and application time of veneering restorations on calcium silicate cements are important factors which influence the interfacial properties. The aim of this study was to measure the micro-shear bond strength of a resin composite (RC) using several adhesive systems and a resin-modified glass ionomer cement (RM-GIC) to different aged Biodentine specimens. Methods and Materials: A total of 15 Biodentine blocks were prepared and assigned to three aging periods: 12 min, one week and one month. Then they were subdivided into five sub-groups to receive cylinders of resinous materials. RC was applied using different adhesive systems: A) no adhesive B) etch and rinse C) two-step self-etch and D) universal adhesive in self-etch mode and E) RM-GIC applied directly over Biodentine. Micro-shear bond strength was measured and the data were analyzed using one-way and two-way ANOVA. The level of significance was set at 0.05. Result: There was significant interaction between Biodentine aging periods and resinous materials (P<0.05). The highest value was obtained in group D bonded to the recently set Biodentine. Increasing the aging period to one week resulted in increased micro-shear bond strength in all groups expect for group D. One-month incubation time led to reduced shear bond strength in group A, C and D. Micro-shear bond strength values of group E increased to the longer aged Biodentine. Conclusion: Group D showed the highest bond strength to freshly mixed Biodentine.Keywords: Bond Strength; Composite Resin; Dental Adhesive; Glass Ionomer Cement; Tricalcium Silicat

Comparative evaluation of the effects of three hydraulic calcium silicate cements on odontoblastic differentiation of human dental pulp stem cells: an in vitro study

Objective: The study aimed to compare the response of human dental pulp stem cells (hDPSCs) towards three hydraulic calcium silicate cements (HCSCs) by measuring cytotoxicity and expression of dentinogenic genes. Methodology: Dental pulps of five impacted mandibular third molars were extirpated as a source for hDPSCs. Next to culturing, hDPSCs were subjected to fluorescence-activated cell sorting after the third passage to validate stemness of the cells. Human DPSCs were exposed to diluted supernatants of OrthoMTA (OMTA), Biodentine (BD) and Calcium-Enriched Mixture (CEM) at concentrations 10, 25, 50 and 100% at the first, third and fifth day of culture. Then, cells were exposed to 10% concentrations supernatant of HCSCs to determine DSPP and DMP1 gene expression, using a quantitative polymerase-chain reaction. Data were analyzed using one-way and three-way ANOVA, followed by Tukey post hoc statistical tests. Results: Optimal cell proliferation was observed in all groups, regardless of concentration and time-point. HCSC supernatants were non-cytotoxic to hDPSCs at all three time-points, except for 100% Biodentine on day five. On day seven, OMTA group significantly upregulated the expression of DSPP and DMP1 genes. On day 14, expression of DMP1 and DSPP genes were significantly higher in BD and OMTA groups, respectively. Conclusion: Biodentine significantly upregulated DMP1 gene expression over 14 days, whereas CEM was associated with only minimal expression of DSPP and DMP1 . &nbsp

SEM analysis of MTAD efficacy for smear layer removal from periodontally affected root surfaces

Objective: Biopure® MTAD (Dentsply Tulsa Dental, USA) has been developedas a final irrigant following root canal shaping to remove intracanal smear layer.Many of the unique properties of MTAD potentially transfer to the conditioningprocess of tooth roots during periodontal therapy. The aim of this ex vivo studywas to evaluate the effect of MTAD on the removal of smear layer from root surfaces.Materials and Methods: Thirty two longitudinally sectioned specimens from 16freshly extracted teeth diagnosed with advanced periodontal disease were dividedinto four groups. In group 1 and 2, the root surfaces were scaled using Gracey curettes.In group 3 and 4, 0.5 mm of the root surface was removed using a fissurebur. The specimens in group 1 and 3 were then irrigated by normal saline. Thespecimens in groups 2 and 4 were irrigated with Biopure MTAD.All specimens were prepared for SEM and scored according to the presence ofsmear layer.Results: MTAD significantly increased (P=0.001) the smear layer removal inboth groups 2 and 4 compared to the associated control groups, in which only salinewas used.Conclusion: MTAD increased the removal of the smear layer from periodontallyaffected root surfaces. Use of MTAD as a periodontal conditioner may be suggeste

Comparative evaluation of the effects of three hydraulic calcium silicate cements on odontoblastic differentiation of human dental pulp stem cells: an in vitro study

Objective The study aimed to compare the response of human dental pulp stem cells (hDPSCs) towards three hydraulic calcium silicate cements (HCSCs) by measuring cytotoxicity and expression of dentinogenic genes. Methodology Dental pulps of five impacted mandibular third molars were extirpated as a source for hDPSCs. Next to culturing, hDPSCs were subjected to fluorescence-activated cell sorting after the third passage to validate stemness of the cells. Human DPSCs were exposed to diluted supernatants of OrthoMTA (OMTA), Biodentine (BD) and Calcium-Enriched Mixture (CEM) at concentrations 10, 25, 50 and 100% at the first, third and fifth day of culture. Then, cells were exposed to 10% concentrations supernatant of HCSCs to determine DSPP and DMP1 gene expression, using a quantitative polymerase-chain reaction. Data were analyzed using one-way and three-way ANOVA, followed by Tukey post hoc statistical tests. Results Optimal cell proliferation was observed in all groups, regardless of concentration and time-point. HCSC supernatants were non-cytotoxic to hDPSCs at all three time-points, except for 100% Biodentine on day five. On day seven, OMTA group significantly upregulated the expression of DSPP and DMP1 genes. On day 14, expression of DMP1 and DSPP genes were significantly higher in BD and OMTA groups, respectively. Conclusion Biodentine significantly upregulated DMP1 gene expression over 14 days, whereas CEM was associated with only minimal expression of DSPP and DMP1

MicroRNAs-mediated regulation of the differentiation of dental pulp-derived mesenchymal stem cells: a systematic review and bioinformatic analysis

Background: Human dental pulp-derived mesenchymal stem cells (hDP-MSCs), which include human dental pulp stem cells (hDPSCs) and stem cells from human exfoliated deciduous teeth (SHEDs), are promising cell sources for regenerative therapies. Nevertheless, a lack of knowledge relating to the mechanisms regulating their differentiation has limited their clinical application. microRNAs (miRNAs) are important regulatory molecules in cellular processes including cell differentiation. This systematic review aims to provide a panel of miRNAs that regulate the differentiation of hDP-MSCs including hDPSCs and SHEDs. Additionally, bioinformatic analyses were conducted to discover target genes, signaling pathways and gene ontologies associated with the identified miRNAs. Methods: A literature search was performed in MEDLINE (via PubMed), Web of Science, Scopus, Embase and Cochrane Library. Experimental studies assessing the promotive/suppressive effect of miRNAs on the differentiation of hDP-MSCs and studies evaluating changes to the expression of miRNAs during the differentiation of hDP-MSCs were included. miRNAs involved in odontogenic/osteogenic differentiation were then included in a bioinformatic analysis. A miRNA-mRNA network was constructed, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. A protein–protein interaction (PPI) network was also constructed. Results: Of 766 initially identified records through database searching, 42 and 36 studies were included in qualitative synthesis and bioinformatic analyses, respectively. Thirteen miRNAs promoted and 17 suppressed odontogenic/osteogenic differentiation of hDP-MSCs. hsa-miR-140-5p, hsa-miR-218 and hsa-miR-143 were more frequently reported suppressing the odontogenic/osteogenic differentiation of hDP-MSCs. hsa-miR-221 and hsa-miR-124 promoted and hsa-miR-140-5p inhibited neuronal differentiation, hsa-miR-26a-5p promoted and hsa-miR-424 suppressed angiogenic differentiation, and hsa-miR-135 and hsa-miR-143 inhibited differentiation within myogenic lineages. A miRNA-mRNA network including 1890 nodes and 2171 edges was constructed. KEGG pathway analysis revealed MAPK, PI3K-Akt and FoxO as key signaling pathways involved in the odontogenic/osteogenic differentiation of hDP-MSCs. Conclusions: The findings of this systematic review support the potential application of the specific miRNAs to regulate the directed differentiation of hDP-MSCs in the field of regenerative therapies

Differentiation of human endometrial stem cells encapsulated in alginate hydrogel into oocyte-like cells

Introduction: Human endometrial mesenchymal stem cells (hEnMSCs) are a rich source of mesenchymal stem cells (MSCs) with multi-lineage differentiation potential, making them an intriguing tool in regenerative medicine, particularly for the treatment of reproductive and infertility issues. The specific process of germline cell-derived stem cell differentiation remains unknown, the aim is to study novel ways to achieve an effective differentiation method that produces adequate and functioning human gamete cells. Methods: We adjusted the optimum retinoic acid (RA) concentration for enhancement of germ cell-derived hEnSCs generation in 2D cell culture after 7 days in this study. Subsequently, we developed a suitable oocyte-like cell induction media including RA and bone morphogenetic protein 4 (BMP4), and studied their effects on oocyte-like cell differentiation in 2D and 3D cell culture media utilizing cells encapsulated in alginate hydrogel. Results: Our results from microscopy analysis, real-time PCR, and immunofluorescence tests revealed that 10 µM RA concentration was the optimal dose for inducing germ-like cells after 7 days. We examined the alginate hydrogel structural characteristics and integrity by rheology analysis and SEM microscope. We also demonstrated encapsulated cell viability and adhesion in the manufactured hydrogel. We propose that in 3D cell cultures in alginate hydrogel, an induction medium containing 10 µM RA and 50 ng/mL BMP4 can enhance hEnSC differentiation into oocyte-like cells. Conclusion: The production of oocyte-like cells using 3D alginate hydrogel may be viable in vitro approach for replacing gonad tissues and cells