Optical effects of graphene addition on adhesives for orthodontic lingual retainers.

The objective of this study was to determine the effects on the colour of adding increasing concentrations of graphene to orthodontic fixed retainer adhesives and to evaluate changes in optical transmission during light curing and the resultant degree of conversion. Two different types of adhesives commonly used for fixed retainers were investigated: A packable composite (Transbond) and a flowable composite (Transbond Supreme). Graphene was added to the adhesives in three different concentrations (0.01, 0.05, and 0.1 wt%). Adhesives without graphene addition were set as control groups. A Minolta colourimeter was used to measure the colour and translucency parameters. Irradiance transmitted during curing was quantified using MARC Light Collector. Fourier-transform infrared spectroscopy was used to record degree of conversion. Data were statistically analysed with the Student's t-test and one-way ANOVA with Tukey's tests (α = 0.05). The findings showed that incorporating graphene darkened the adhesive colour significantly and reduced translucency. As the graphene concentration reached 0.1 wt%, samples became opaque; yet, no adverse effect on degree of conversion was observed. The addition of graphene reduces optical transmission of lingual retainer adhesives; the effect increases with graphene concentration.

Biofabrication, biochemical profiling, and in vitro applications of salivary gland decellularized matrices via magnetic bioassembly platforms.

Trending three-dimensional tissue engineering platforms developed via biofabrication and bioprinting of exocrine glands are on the rise due to a commitment to organogenesis principles. Nevertheless, a proper extracellular matrix (ECM) microarchitecture to harbor primary cells is yet to be established towards human salivary gland (SG) organogenesis. By using porcine submandibular gland (SMG) biopsies as a proof-of-concept to mimic the human SG, a new decellularized ECM bioassembly platform was developed herein with varying perfusions of sodium dodecyl sulfate (SDS) to limit denaturing events and ensure proper preservation of the native ECM biochemical niche. Porcine SMG biopsies were perfused with 0.01%, 0.1%, and 1% SDS and bio-assembled magnetically in porous polycarbonate track-etched (PCTE) membrane. Double-stranded DNA (dsDNA), cell removal efficiency, and ECM biochemical contents were analyzed. SDS at 0.1% and 1% efficiently removed dsDNA (< 50 ng/mg) and preserved key matrix components (sulfated glycosaminoglycans, collagens, elastin) and the microarchitecture of native SMG ECM. Bio-assembled SMG decellularized ECM (dECM) perfused with 0.1-1% SDS enhanced cell viability, proliferation, expansion confluency rates, and tethering of primary SMG cells during 7 culture days. Perfusion with 1% SDS promoted greater cell proliferation rates while 0.1% SDS supported higher acinar epithelial expression when compared to basement membrane extract and other substrates. Thus, this dECM magnetic bioassembly strategy was effective for decellularization while retaining the original ECM biochemical niche and promoting SMG cell proliferation, expansion, differentiation, and tethering. Altogether, these outcomes pave the way towards the recellularization of this novel SMG dECM in future in vitro and in vivo applications.

Identifying potential immuno-oncology targets in salivary gland mucoepidermoid carcinoma based on inflammatory status and treatment response.

BACKGROUND: Mucoepidermoid carcinoma is a rare salivary gland malignant tumour. This study aimed to investigate inflammatory and immune signatures of mucoepidermoid carcinoma by identifying potential proteo-transcriptomic biomarkers towards the development of precision immuno-oncology treatment strategies. METHODS: A total of 30 biopsies obtained from patients diagnosed with mucoepidermoid carcinoma between 2013 and 2022 were analysed after H&E staining for scoring of histological inflammatory stroma subtypes and inflammatory hotspots with QuPath. Multiplex immunofluorescence staining and NanoString nCounter PanCancer IO 360™ panel were used to assess stroma and tumour inflammation signatures in high grade mucoepidermoid carcinoma cases in the tumour microenvironment via proteomics and transcriptomics, respectively. RESULTS: Inflammatory cells within the histological inflammatory stroma inflammatory (HIS-INF/hot) tumour neighbourhoods were greater compared to the histological inflammatory stroma-immune desert (HIS-ID/cold) (p = 0.001). A similar trend was observed between treatment non-responders and responders in stroma neighbourhoods (p = 0.0625) and in stroma-to-interface inflammatory hotspots (p = 0.0081), indicating an augmented inflammatory response in hot tumours and non-responders. Furthermore, there were striking differences in the expression of pan-immune leukocyte marker CD45 between responders and non responders particularly in the tumour neighbourhoods (p = 0.0341), but such were not robust for PD-1 and macrophage fractions. Additionally, transcriptomic analysis revealed key differences in leukocyte activation profiles between responders and non-responders. CONCLUSION: This preliminary report unveils the importance of assessing immune leukocyte cellular fractions and pathways for future prognostic biomarker discoveries in mucoepidermoid carcinoma as per the involvement of CD45-driven inflammatory and immune mediators in high grade mucoepidermoid carcinoma in non-responders to treatment. These findings will potentially contribute to the development of novel personalised immunotherapies.

Genome-Based Characterization of Multidrug-Resistant Escherichia coli Isolated from Clinical Bovine Mastitis.

Mastitis occurrence in dairy cows is a broad topic that involves several sectors, from antimicrobial resistance and virulence of strains to economic implications and cattle management practices. Here, we assessed the molecular characterization (antimicrobial resistance determinants, virulence genes, sequences type, serotypes, and plasmid types) of 178 Escherichia coli strains isolated from milk samples from cows with clinical mastitis using a genome-based k-mers approach. Of these, 53 (29.8%) showed multidrug resistance by disc diffusion. We selected eight multidrug-resistant mastitis-associated E. coli for whole-genome sequencing and molecular characterization based on raw data using k-mers. We assessed antimicrobial resistance genes, virulence factors, serotypes, Multilocus Sequence Typing (MLST), and plasmid types. The most antimicrobial resistance gene found were blaTEM-1B (7/8), tetA (6/8), strA (6/8), strB (6/8), and qnrB19 (5/8). A total of 25 virulence factors were detected encoding adhesins, capsule, enzymes/proteins, increased serum survival, hemolysin, colicins, and iron uptake. These virulence factors were associated with Extraintestinal Pathogenic E. coli. Three pandemic clones were found: ST10, ST101, and ST69. Two E. coli were assigned in the O117 serogroup and one in the O8:H25 serotype. The most common plasmid groups were IncFII (7/8) and IncFIB (6/8). Our findings contribute to the knowledge of virulence mechanisms, epidemiological aspects, and antimicrobial resistance determinants of E. coli strains obtained from clinical mammary infections of cows.

A critical analysis of research methods and biological experimental models to study pulp regeneration.

With advances in knowledge and treatment options, pulp regeneration is now a clear objective in clinical dental practice. For this purpose, many methodologies have been developed in attempts to address the putative questions raised both in research and in clinical practice. In the first part of this review, laboratory-based methods will be presented, analysing the advantages, disadvantages, and benefits of cell culture methodologies and ectopic/semiorthotopic animal studies. This will also demonstrate the need for alignment between two-dimensional and three-dimensional laboratory techniques to accomplish the range of objectives in terms of cell responses and tissue differentiation. The second part will cover observations relating to orthotopic animal studies, describing the current models used for this purpose and how they contribute to the translation of regenerative techniques to the clinic.

Concentration of essential and toxic elements as a function of the depth of the soil and the presence of fulvic acids in a wetland in Cerrado, Brazil.

The protection of wetlands is essential for sustainable development. The particular hydrology of wetlands creates conditions for the formation of hydric soils. Hydric soils are formed in oxide-reducing environments and perform important removal and re-oxidation of Fe and Mn oxides and hydroxides. They are also characterized by the formation of a superficial horizon enriched by the accumulation of organic matter. The objective of this study was to determine the concentration of essential (Co, Cu, Fe, Mn, Ni, Zn) and toxic (Al, Cd, Pb) elements in the soil solution in a wetland, surrounded by an intense agricultural activity area. The concentrations of the elements were evaluated according to the level of hydromorphy (border to the center) and the depth of the soil. The physical fractionation of these elements was also assessed (total and < 30 kDa), and the results were compared with the chemical speciation of these elements. Despite the high total concentrations of Al and Fe, the concentration of these elements was very low in the < 30 kDa fraction, which suggests that these elements are complexed with organic matter, in the form of hydroxides. Evidence of removal of Fe and Mn from the surface horizon was observed at the center of the wetland, where the highest level of hydromorphy is found. The results showed that the concentration of metals in the fraction < 30 kDa is insignificant, suggesting that the mechanisms of precipitation and/or adsorption to soil colloids play an important role in the regulation of this ecosystem.

Graphene-Induced Osteogenic Differentiation Is Mediated by the Integrin/FAK Axis.

Graphene is capable of promoting osteogenesis without chemical induction. Nevertheless, the underlying mechanism(s) remain largely unknown. The objectives here were: (i) to assess whether graphene scaffolds are capable of supporting osteogenesis in vivo and; (ii) to ascertain the participation of the integrin/FAK mechanotransduction axis during the osteogenic differentiation induced by graphene. MSC-impregnated graphene scaffolds (n = 6) were implanted into immunocompromised mice (28 days). Alternatively, MSCs were seeded onto PDMS substrates (modulus of elasticity = 130, 830 and 1300 kPa) coated with a single monomolecular layer of graphene and cultured in basal medium (10 days). The ensuing expressions of FAK-p397, integrin, ROCK1, F-actin, Smad p1/5, RUNX2, OCN and OPN were evaluated by Western blot (n = 3). As controls, MSCs were plated onto uncoated PDMS in the presence of mechanotransduction inhibitors (echistatin, Y27632 and DMH1). MSC-impregnated graphene scaffolds exhibited positive immunoexpression of bone-related markers (RUNX2 and OPN) without the assistance of osteogenic inducers. In vitro, regardless of the stiffness of the underlying PDMS substrate, MSCs seeded onto graphene-coated PDMS substrates demonstrated higher expressions of all tested osteogenic and integrin/FAK proteins tested compared to MSCs seeded onto PDMS alone. Hence, graphene promotes osteogenesis via the activation of the mechanosensitive integrin/FAK axis.

Streptococcus mutans forms xylitol-resistant biofilm on excess adhesive flash in novel ex-vivo orthodontic bracket model.

INTRODUCTION: During orthodontic bonding procedures, excess adhesive is invariably left on the tooth surface at the interface between the bracket and the enamel junction; it is called excess adhesive flash (EAF). We comparatively evaluated the biofilm formation of Streptococcus mutans on EAF produced by 2 adhesives and examined the therapeutic efficacy of xylitol on S mutans formed on EAF. METHODS: First, we investigated the biofilm formation of S mutans on 3 orthodontic bracket types: stainless steel preadjusted edgewise, ceramic preadjusted edgewise, and stainless steel self-ligating. Subsequently, tooth-colored Transbond XT (3M Unitek, Monrovia, Calif) and green Grengloo (Ormco, Glendora, Calif) adhesives were used for bonding ceramic brackets to extracted teeth. S mutans biofilms on EAF produced by the adhesives were studied using the crystal violet assay and scanning electron microscopy. Surface roughness and surface energy of the EAF were examined. The therapeutic efficacies of different concentrations of xylitol were tested on S mutans biofilms. RESULTS: Significantly higher biofilms were formed on the ceramic preadjusted edgewise brackets (P = 0.003). Transbond XT had significantly higher S mutans biofilms compared with Grengloo surfaces (P = 0.007). There was no significant difference in surface roughness between Transbond XT and Grengloo surfaces (P >0.05). Surface energy of Transbond XT had a considerably smaller contact angle than did Grengloo, suggesting that Transbond XT is a more hydrophilic material. Xylitol at low concentrations had no significant effect on the reduction of S mutans biofilms on orthodontic adhesives (P = 0.016). CONCLUSIONS: Transbond XT orthodontic adhesive resulted in more S mutans biofilm compared with Grengloo adhesive on ceramic brackets. Surface energy seemed to play a more important role than surface roughness for the formation of S mutans biofilm on EAF. Xylitol does not appear to have a therapeutic effect on mature S mutans biofilm.

Effects of chrondro-osseous regenerative compound associated with local treatments in the regeneration of bone defects around implants: an in vivo study.

OBJECTIVES: The objective of this study was to evaluate the use of a chondroitin sulfate and glycosaminoglycan-based chrondro-osseous regenerative compound (CORC) with different local treatments for bone regeneration in dehiscence defects. The hypothesis is that CORC can enhance bone regeneration with or without local treatment. MATERIALS AND METHODS: Twelve mongrel dogs received four implants each in the right femur. Bony defects (4-mm height × 4-mm width) were created and locally treated as follows: reabsorbable membrane (Mem), hidroxyapatite (HA), hydroxyapatite covered with membrane (HA+Mem), or left untreated (Con). Six dogs received one pill of the CORC daily. After 90 days, the implants were retrieved, and histological sections were obtained. The height of bone formation, new bone area (NBA), and bone to implant contact (BIC) within the threads were evaluated to assess the effects of the use of CORC to promote bone regeneration in the defects. Results were statistically analyzed using ANOVA and Tukey's test with 5% significance level. RESULTS: CORC was not capable to increase the height of bone formation, NBA, and BIC. When the local treatments were analyzed regardless of the use of CORC, HA+Mem and Ha presented higher BIC and height of bone formation. There was no difference for NBA among the local treatments. CONCLUSIONS: The hypothesis was rejected since the use of CORC has not increased any of the parameters evaluated. CLINICAL RELEVANCE: Dehiscence-like defects can compromise soft tissue support and result in loss of periodontal health and implants. Hydroxyapatite can induce bone regeneration in the defects created. CORC in the formulation used in this study did not promote further bone regeneration in dehiscence-like defects.

Structural reinforcement and sealing ability of temporary fillings in premolar with class II mod cavities.

AIM: To evaluate the capability to reinforce tooth structure and sealing ability of temporary filling materials in premolars with MOD cavities. The hypothesis is that temporary filling materials can concomitantly prevent microleakage and increase fracture resistance. MATERIALS AND METHODS: Premolars received root canal treatment and MOD cavities. Cavities were restored with non- eugenol cement (CIM), glass ionomer cement (GIC) or light curable composite (BIO). Higid and without restoration were controls. Materials for flexual strength and teeth were tested for microleakage and compressive strength. RESULTS: GIC and Higid presented similar compressive strength, higher than other groups. Bio and GIC presented similar flexural strength higher than BIO. CIM and BIO showed similar micro- leakage lower than GIC. CONCLUSION: The hypothesis was rejected as filling materials tested failed to prevent microleakage and to increase fracture resistance concomitantly. CLINICAL SIGNIFICANCE: GIC may be considered to restore weakened teeth subjected to occlusal loads. BIO and CIM are better choices to microleakage in teeth not subjected to mechanical stresses.

Boron-containing coating yields enhanced antimicrobial and mechanical effects on translucent zirconia.

OBJECTIVES: To evaluate the mechanical and antimicrobial properties of boron-containing coating on translucent zirconia (5Y-PSZ). METHODS: 5Y-PSZ discs (Control) were coated with a glaze (Glaze), silver- (AgCoat), or boron-containing (BCoat) glasses. The coatings' antimicrobial potential was characterized using S. mutans biofilms after 48 h via viable colony-forming units (CFU), metabolic activity (CV) assays, and quantification of extracellular polysaccharide matrix (EPS). Biofilm architectures were imaged under scanning electron and confocal laser scanning microscopies (SEM and CLSM). The cytocompatibility was determined at 24 h via WST-1 and LIVE&DEAD assays using periodontal ligament stem cells (PDLSCs). The coatings' effects on properties were characterized by Vickers hardness, biaxial bending tests, and fractography analysis. Statistical analyses were performed via one-way ANOVA, Tukey's tests, Weibull analysis, and Pearson's correlation analysis. RESULTS: BCoat significantly decreased biofilm formation, having the lowest CFU and metabolic activity compared with the other groups. BCoat and AgCoat presented the lowest EPS, followed by Glaze and Control. SEM and CLSM images revealed that the biofilms on BCoat were thin and sparse, with lower biovolume. In contrast, the other groups yielded robust biofilms with higher biovolume. The cytocompatibility was similar in all groups. BCoat, AgCoat, and Glaze also presented similar hardness and were significantly lower than Control. BCoat had the highest flexural strength, characteristic strength and Weibull parameters (σF: 625 MPa; σ0: 620 MPa; m = 11.5), followed by AgCoat (σF: 464 MPa; σ0: 478 MPa; m = 5.3). SIGNIFICANCE: BCoat is a cytocompatible coating with promising antimicrobial properties that can improve the mechanical properties and reliability of 5Y-PSZ.

What and where are the stem cells for Dentistry?

Disinfection of root canals followed by the replacement of the infected or inflamed pulp tissues by inert materials is the foundation for treating irreversible damaged dental pulps. The management of pathological conditions of the periodontium is mainly based solely upon infection control via the reestablishment of oral hygiene, scaling and root planing to control inflammation which stops progressive bone loss. As one may see, the clinical management of endodontic and periodontal diseases has not changed drastically despite the development of new materials, techniques and medicaments. Tissue engineering is a multi-disciplinary field focused on the development of materials, techniques and strategies to improve or replace damaged or lost biological functions and tissues. As the tissue engineering field progresses, "scaffolds", "suggest pathways" and "stem cells" abandoned their role as technical words exclusively used by scientists and slowly assume a part in the language of students, educators, clinicians and patients. However the unfamiliarity with some of the concepts can lead to misinterpretations of the current status and overexcitement about future applications of stem cells for dental-related tissue regeneration. This paper will present a panorama and the future challenges on the path to use of stem cells for endodontic and periodontal tissue regeneration.

Effect of two graphene derivatives on Enterococcus faecalis biofilms and cytotoxicity.

This study investigated the antibacterial efficacy and cytotoxicity of two graphene derivatives -graphene oxide (GO) and reduced graphene oxide (RGO)- against Enterococcus faecalis (E. faecalis) in biofilms formed on hydroxyapatite discs. The viability and biomass of biofilms treated with GO or RGO were evaluated by colony-forming unit counting and crystal violet staining. The morphological features of the biofilms were observed by scanning electron microscopy (SEM), and the bio-volume was quantitatively analyzed by confocal laser scanning microscopy. Furthermore, the cytotoxicity of GO and RGO was evaluated. GO and RGO had similar antibacterial effects on E. faecalis in biofilms (p>0.05). The SEM images showed the ability of GO and RGO to disrupt E. faecalis. Furthermore, GO had significantly higher cytotoxicity than RGO (p<0.05). The results suggest that RGO has the potential to be used as a more effective disinfecting agent than GO since it showed less cytotoxicity while exerting similar antibacterial efficacy.

Salivary gland regeneration: from salivary gland stem cells to three-dimensional bioprinting.

Hyposalivation and severe dry mouth syndrome are the most common complications in patients with head and neck cancer (HNC) after receiving radiation therapy. Conventional treatment for hyposalivation relies on the use of sialogogues such as pilocarpine; however, their efficacy is constrained by the limited number of remnant acinar cells after radiation. After radiotherapy, the salivary gland (SG) secretory parenchyma is largely destroyed, and due to the reduced stem cell niche, this gland has poor regenerative potential. To tackle this, researchers must be able to generate highly complex cellularized 3D constructs for clinical transplantation via technologies, including those that involve bioprinting of cells and biomaterials. A potential stem cell source with promising clinical outcomes to reserve dry mouth is adipose mesenchymal stem cells (AdMSC). MSC-like cells like human dental pulp stem cells (hDPSC) have been tested in novel magnetic bioprinting platforms using nanoparticles that can bind cell membranes by electrostatic interaction, as well as their paracrine signals arising from extracellular vesicles. Both magnetized cells and their secretome cues were found to increase epithelial and neuronal growth of in vitro and ex vivo irradiated SG models. Interestingly, these magnetic bioprinting platforms can be applied as a high-throughput drug screening system due to the consistency in structure and functions of their organoids. Recently, exogenous decellularized porcine ECM was added to this magnetic platform to stimulate an ideal environment for cell tethering, proliferation, and/or differentiation. The combination of these SG tissue biofabrication strategies will promptly allow for in vitro organoid formation and establishment of cellular senescent organoids for aging models, but challenges remain in terms of epithelial polarization and lumen formation for unidirectional fluid flow. Current magnetic bioprinting nanotechnologies can provide promising functional and aging features to in vitro craniofacial exocrine gland organoids, which can be utilized for novel drug discovery and/or clinical transplantation.

Dual trigger and the impact on oocyte quality and embryo development: a Brazilian cohort.

OBJECTIVE: We aimed to analyze controlled ovarian stimulation using GnRH antagonist in association with hCG (dual triggering) versus hCG alone (conventional triggering) for final oocyte maturation triggering in a population of unselected Brazilian women. METHODS: This was a retrospective observational study of IVF medical records between January 2019 and March 2020. Data from 335 women with infertility were included for study. All patients were divided into hCG trigger (control group; n=178) and dual trigger (n=157). RESULTS: The number of total oocytes and the number of inseminated oocytes were all significantly higher with the dual trigger protocol compared to hCG-only trigger. However, there is no significant difference in patient age, type of infertility, number of in vitro matured oocytes, trigger day, endometrial thickness, AMH concentration, the number of follicles, the number of mature oocytes and the number of fertilized oocytes. CONCLUSIONS: Using the dual trigger protocol improved the number of total oocytes retrieved and the number of inseminated oocytes.

Impact of Body Mass Index and advanced maternal age on in vitro fertilization outcomes.

OBJECTIVE: To evaluate the impact of body mass index associated with advanced maternal age on pregnancy outcomes. METHODS: A retrospective and observational study that included 808 in vitro fertilization cycles and evaluated: age, weight, height, number of oocytes and mature oocytes, number of embryos and transferred embryos, fertilization and clinical pregnancy rates. Four categories of body mass index: underweight, adequate weight, overweight and obesity. We classified age into 4 categories: 35-37; 38-40; 41-42 and over 42 years of age. The means and rates were calculated and compared between different ages and body mass index groups. RESULTS: For the fresh group, women who achieved clinical pregnancy had a lower mean age than those who did not become pregnant, being the higher the pregnancy rate the lower the age (p<0.0001). After logistic regression analysis for data associated with clinical pregnancy in the fresh group, the number of transferred embryos remained higher in the overweight category (p=0.0001). Overweight and obese women had a significantly higher rate of mature oocytes when compared with adequate weight (p=0.015). Analysis using the ROC curve indicated an area under the curve of 60% (p=0.002) for the fresh group. CONCLUSIONS: The adverse effect of high BMI on clinical pregnancy rates is greater in women under 35 years compared to older women; and age had a higher impact on live birth rate rather than BMI, when the analysis was performed on older women, with the impact of BMI on the probability of having a live birth depending on maternal age.

Graphene oxide increases PMMA's resistance to fatigue and strength degradation.

OBJECTIVES: to characterize the effects of graphene oxide (GO) on polymethyl methacrylate's (PMMA) reliability and lifetime. The hypothesis tested was that GO would increase both Weibull parameters and decreased strength degradation over time. METHODS: PMMA disks containing GO (0.01, 0.05, 0.1, or 0.5 wt%) were subjected to a biaxial flexural test to determine the Weibull parameters (m: modulus of Weibull; σ0: characteristic strength; n = 30 at 1 MPa/s) and slow crack growth (SCG) parameters (n: subcritical crack growth susceptibility coefficient, σf0: scaling parameter; n = 10 at 10-2, 10-1, 101, 100 and 102 MPa/s). Strength-probability-time (SPT) diagrams were plotted by merging SCG and Weibull parameters. RESULTS: There was no significant difference in the m value of all materials. However, 0.5 GO presented the lowest σ0, whereas all other groups were similar. The lowest n value obtained for all GO-modified PMMA groups (27.4 for 0.05 GO) was higher than the Control (15.6). The strength degradation predicted after 15 years for Control was 12%, followed by 0.01 GO (7%), 0.05 GO (9%), 0.1 GO (5%), and 0.5 GO (1%). SIGNIFICANCE: The hypothesis was partially accepted as GO increased PMMA's fatigue resistance and lifetime but did not significantly improve its Weibull parameters. GO added to PMMA did not significantly affect the initial strength and reliability but significantly increased PMMA's predicted lifetime. All the GO-containing groups presented higher resistance to fracture at all times analyzed compared with the Control, with the best overall results observed for 0.1 GO.

Specimen Shape and Elution Time Affect the Mineralization and Differentiation Potential of Dental Pulp Stem Cells to Biodentine.

The liquid extract method is commonly used to evaluate the cytotoxicity and bioactivity of materials. Although ISO has recommended guidelines for test methods, variations in elution period, and shape of samples can influence the biological outcomes. The aim of this study was to investigate the influence of material form and elution period of Biodentine on dental pulp stem cells (DPSCs)' proliferation and mineralization. Biodentine (0.2 g) discs or powder were immersed in culture media (10 mL) for 1, 3 or 7 days (D1, D3 and D7). The eluents were filtered and used to treat DPSC. The calcium release profile and pH were determined. Cell proliferation was evaluated by MTS for 3 days, and mineralization and differentiation were assessed by alizarin red S staining (Ca2+/ng of DNA) and qRT-PCR (MEPE, DSPP, DMP-1, RUNX2, COL-I and OCN) for 14 days. Statistical analysis was performed with a one or two-way ANOVA and post hoc Tukey's test (pH, calcium release and proliferation) or Mann-Whitney test (α = 0.05). pH and calcium ion release of powdered eluents were significantly higher than disc eluents. Powdered eluent promoted extensive cell death, while the disc form was cytocompatible. All disc eluents significantly increased the gene expression and mineralization after 14 days compared to the untreated control. D7 induced less mineralization and differentiation compared to D1 and D3. Thus, the materials' form and elution time are critical aspects to be considered when evaluating the bioactivity of materials, since this binomial can affect positively and negatively the biological outcomes.

Mesenchymal stromal cell exosomes enhance dental pulp cell functions and promote pulp-dentin regeneration.

Mesenchymal stromal/stem cell (MSC) therapies are currently being explored for dental pulp regeneration. As the therapeutic effects of MSCs in tissue repair are mediated mainly through the release of extracellular vesicles (EVs) including exosomes, we investigated here the cellular processes and molecular mechanisms modulated by MSC exosomes in dental pulp regeneration. Using dental pulp cell (DPC) cultures, we demonstrated that MSC exosomes could increase DPC migration, proliferation, and odontogenic differentiation. The enhancement of these cellular processes was mediated through exosomal CD73-mediated adenosine receptor activation of AKT and ERK signaling. Consistent with these observations, MSC exosomes increased the expression of dentin matrix proteins and promoted the formation of dentin-like tissue and bridge-like structures in a rat pulp defect model. These effects were comparable to that of mineral trioxide aggregate (MTA) treatment. MSC exosomes also yielded recellularized pulp-dentin tissues in the root canal of endodontically-treated human premolars, following subcutaneous implantation in the mouse dorsum. Together, our findings suggest that MSC exosomes could exert a multi-faceted effect on DPC functions including migration, proliferation and odontogenic differentiation to promote dental pulp regeneration. This study provides the basis for development of MSC exosomes as a cell-free MSC therapeutic alternative for pulp-dentin regeneration.

Regenerating the Dental Pulp-Scaffold Materials and Approaches.

Novel technologies and platforms have allowed significant breakthroughs in dental pulp tissue engineering. The development of injectable scaffolds that can be combined with stem cells, growth factors, or other bioactive compounds has enabled the regeneration of functional dental pulps able to secrete dentin in preclinical and clinical studies. Similarly, cell-homing technologies and scaffold-free strategies aim to modulate dental pulp self-regeneration mediated by resident stem cells and can evade some of the technical challenges related to cell-based tissue engineering strategies. This article will discuss emerging technologies and platforms for the clinical applications of dental pulp tissue engineering.