Low-level laser therapy (LLLT) has been reported to improve cell proliferation and differentiation. The stem cells derived from dental apical papilla (SCAPs) are a promising therapy because they are easily obtained from immature human teeth. The effect of LLLT over SCAPs is still unknown. This study aimed to evaluate the proliferation and osteogenic potential of the SCAPs stimulated with LLLT.

SCAPs were isolated from the third molars of a healthy donor and characterized according to the minimum established criteria. SCAPs were cultured for 24 hours before being exposed to LLLT. Cells were exposed to different doses, energy, and wavelengths for selecting the irradiation parameters. SCAPs proliferation was evaluated with the MTT assay at 24 hours and 7-day post-laser exposure. VEGF and TGF β 2 expression were assessed with a specific enzyme-linked immunosorbent assay (ELISA). The osteogenic differentiation potential was analyzed with alizarin red staining, and the nodule quantification was performed by the relative optical density (ROD) analysis using ImageJ software.

The cells isolated from the apical papilla showed phenotype and stem cell properties. SCAPs irradiated with one dose at 6 J/m 2 and 650 nm exhibited significantly higher proliferation ( P > 0.05) than the controls nonirradiated. LLLT stimulated SCAPs’ expression of factors VEGF and TGF β 2. Also, SCAPs irradiated showed higher osteogenic activity ( P < 0.05).

LLLT promotes proliferation, osteogenic differentiation, and VEGF and TGF β 2 expression on SCAPs. LLLT is a practical approach for the preconditioning of SCAPs in vitro for future regenerative therapies. More studies are needed to determine the underlying molecular processes that determine the mechanism of the LLLT.

This in vitro study assessed and compared the cytotoxicity of mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) cement, Biodentine (BD) and octacalcium phosphate (OCP) on stem cells of the human apical papilla (SCAP). Methods and Materials: SCAPs were isolated from two semi-impacted third molars. The cells were cultured in wells of an insert 24-well plate and were then incubated. The plates were then removed from the incubator and randomly divided into four experimental groups that were exposed to 1-mm discs of set MTA, CEM, BD or OCP, and one untreated control group. After 24, 48 and 168 h, the plates were removed from the incubator and 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) solution was added to each well. Data were analyzed at different time points using the repeated measures ANOVA followed by Bonferroni test and the level of significance was set at 0.05. Cytotoxicity of the four materials was not significantly different from that of the control group at 24, 48 and 168 h (P>0.05). Two-by-two comparison revealed that cytotoxicity of MTA and CEM cement was significantly different from each other at 168 h (P<0.05) although the cytotoxicity of CEM was less than MTA. Cytotoxicity of OCP and MTA was also significantly different from each other at 48 h and OCP had more favorable biocompatibility than MTA (P<0.05). CEM, OCP, BD and MTA showed acceptable biocompatibility when exposed to SCAP. Over time, CEM showed the least cytotoxicity among the materials under study.

Dental pulp capping is a technique that is highly applicable in dental restorations. In this technique, a material is directly placed over the exposed pulp tissue, which promotes pulp healing and generates reparative dentin. Herein, we aimed to investigate the combined effect of different pulp capping agents, including mineral trioxide aggregate (MTA), Emdogain (EMD), calcium-enriched mixture (CEM), and low-level laser therapy (LLLT), on enhancing viability and proliferation of stem cells from apical papilla (SCAPs).

SCAPs were isolated from two immature third molar teeth through collagenase type I enzymatic activity. Isolated stem cells were then cultured with DMEM and α-MEM media enriched with 15% and 10% FBS respectively. After reaching 70%-80% confluency, the cells were seeded in a 96-well plate. Cell viability percent was assessed using the MTT assay after treatment with MTA, EMD, CEM and LLLT (λ = 630 nm, 5 mW, 4 J/cm2) alone and in combination for 24, 48 and 168 hours.

Combination of MTA, CEM, EMD and LLLT resulted in significantly increased SCAPs viability as compared with other treatment groups. Increased SCAPs proliferation and viability were also observed in groups treated with the combination of MTA and CEM with EMD. However, the SCAPs survival rate in all defined time spans was reduced after treatment with MTA and CEM alone.

LLLT can be a stimulator of SCAPs cell viability when applied in combination with dental capping agents such as MTA, EMD and CEM, providing a therapeutic option for stem cell-based dental regeneration.

In this paper, firstly, the CIGSe solar cell with a different Ga/Ga In ratio was modeled based on experimental data using the SCAPS software. Then, the SnS2 composition was proposed as a suitable buffer for the elimination of toxic CdS compounds. According to the modeling results, SnS2 is a very suitable material for substitution of the toxic CdS.

This study assessed the effect of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement on odontogenic differentiation and mineralization of stem cells.
Methods and Materials: After confirmation of stemness and homogeneity of stem cells derived from apical papilla (SCAPs) using flow cytometry, the cells were exposed for 3 weeks to either osteogenic medium (OS) or CEM extract (CEM) or MTA extract in OS (MTA) or DMEM based regular culture media (negative control). Relative expression of alkaline phosphatase (ALP), dentine sialophosphoprotein (DSPP), osteocalcin (OSC), and osterix (SP7) were measured at days 14 and 21 using RT-qPCR method. At the same time points Alizarin Red staining method was used to assess mineralization potential of SCAPS. Gene expression changes analysis were made automatically using REST® software and a P After 2 weeks of exposure, expression of all genes were between 3 and 52 times the expression of GADPH (all were upregulated except SP7 in the control, P After 2 weeks, gene expressions were almost comparable in OS, CEM, and MTA. After 3 weeks, OS and MTA upregulated genes much greater than in 2nd week. However, upregulation in CEM might not increase in 3rd week compared to those in 2nd week.

A tandem solar cell consisting of three cells is designed and simulated by the Solar Cell Capacitor Simulator (SCAPS) program. The bandgap of the top cell absorber (Cs2AgBi0.75Sb0.25Br6) is 1.8 eV, the middle cell absorber (CH3NH3PbI3) has a bandgap of 1.55 eV), and a single-crystal silicon cell (with 1.12 eV bandgap) is selected as the bottom cell. Each of these cells were simulated and optimized separately. To improve current density in the middle cell, CuSCN is chosen as the holetransport layer (HTL). Power conversion efficiencies (PCE) of individual Cs2AgBi0.75Sb0.25Br6, MAPbI3, and Si cells are 14.32%, 25.09%, and 25.22%, respectively. which are quite close to the results published in the literature. Consequently, the tandem structure of these cells is simulated and the optimal thicknesses for the absorber layers (as required by the current-matching condition) in a two-terminal (2T) monolithic structure is calculated. The optimized thicknesses of Cs2AgBi0.75Sb0.25Br6 and MAPbI3 absorber layers in the tandem configuration are 300 and 550 nm, respectively. The transmitted spectra of the top and middle cells are obtained using the Matlab software. Subsequently, the SCAPS numerical simulation for the 2T tandem structure gave an enhanced power conversion efficiency (PCEs) of 38.9%.

Assessment of the cytotoxicity of novel calcium silicate-based cement is imperative in endodontics. This experimental study aimed to assess the cytotoxicity and odontogenic/osteogenic differentiation potential of a new calcium silicate/pectin cement called Nano-dentine against stem cells from the apical papilla (SCAPs).

In this experimental study, the cement powder was synthesized by the sol-gel technique. Zirconium oxide was added as opacifier and Pectin, a plant-based polymer, and calcium chloride as the liquid to prepare the nano-based dental cement. Thirty-six root canal dentin blocks of human extracted single-canal premolars with 2 mm height, flared with #1, 2 and 3 Gates-Glidden drills were used to prepare the cement specimens. The cement, namely mineral trioxide aggregate (MTA), Biodentine, and the Nano-dentine were mixed according to the manufacturers’ instructions and applied to the roots of canal dentin blocks. The cytotoxicity and odontogenic/osteogenic potential of the cement were evaluated by using SCAPs.

SCAPs were characterized by the expression of routine mesenchymal cell markers and differentiation potential to adipocytes, osteoblasts, and chondrocytes. Cement displayed no significant differences in cytotoxicity or calcified nodules formation. Gene expression analysis showed that all three types of cement induced significant downregulation of COLA1; however, the new cement induced significant up-regulation of RUNX2 and SPP1 compared to the control group and MTA. The new cement also induced significant up-regulation of TGFB1 and inducible nitric oxide synthase (iNOS) compared with Biodentine and MTA.

The new Nano-dentin cement has higher odontogenic/osteogenic potential compared to Biodentine and MTA for differentiation of SCAPs to adipocytes, osteoblasts, and chondrocytes.

The studies show that despite implementing good vehicle maintenance activities in traffic police, these activities are not goal-directed. The current research entitled ‘A survey of the Maintenance situation of Traffic Police Vehicles Based on SCAP Model’ was accomplished to determine the gap between the current maintenance situation and the ideal situation. The research method is a field one. The data was gathered using questionnaires from the statistical population. After defining research variables, variable factors were selected. Then, having measured the validity and reliability of the questionnaires, they were distributed and gathered. The results of the research show that the current maintenance situation of traffic police vehicles is far removed from the ideal situation. It is suggested that the managers should improve the level of knowledge, skill and technical information of maintenance employees in order to reach the ideal situation. Also, employing skilled and knowledgeable managers to lead the vehicle maintenance system will be effective.

It is known that Hertwig's epithelial root sheath and stem cells of apical papilla (SCAP) can organize the odontoblast cells under favorable conditions resulting in continued formation of the root even after the pulp is necrotic. The aim of this case report was to demonstrate the continued development of the roots of an immature permanent tooth with necrotic pulp subsequent to conservative root canal treatment.Case report: The patient was an 8-year-old healthy boy with a severe carious lesion in the lower left first molar tooth with an immature root. The tooth underwent a conservative treatment approach, i.e. minimal filling with (k-files: stainless steel, Mani- Japan) and copious 2.5% NaOCl irrigation and then was medicated with calcium hydroxide (U.S.P. Sultan-USA). In this case, after one year developed mature apices was observed without any complication. It is hoped that in the future, regeneration and stimulation of normal continued root development in necrotic immature teeth will replace apexification. Procedures and much fewer cases of cervical fractures of the crown and root and improper root/crown ratios will be encountered.

Root canal disinfection is an important step in regenerative endodontic treatments. An ideal irrigating solution must have high antimicrobial activity and minimum cytotoxicity. This study sought to assess the effect of some irrigating solutions on stem cells from the human apical papilla (SCAP) after different periods of exposure.
Methods and Materials: Stem cells were isolated from immature, impacted mandibular third molars, transferred to 24-well plates, randomly divided into 6 experimental groups and exposed to BioPure MTAD Cleanser, QMix, 17% EDTA, 2% chlorhexidine (CHX), 5.25% sodium hypochlorite (NaOCl), sterile saline and untreated control group. Cytotoxicity of these solutions was assessed after 1, 5 and 15 min of exposure using the methyl thiazol tetrazolium (MTT) assay. Data were statistically analyzed using repeated measures ANOVA. Level of significance was set at 0.05.
The mean percentage of viable cells in all experimental groups was significantly different from the control and sterile saline groups at all the time points (PEDTA>QMax=NaOCl>CHX> sterile saline.
Chlorhexidine had the lowest cytotoxicity compared to EDTA, MTAD, QMix and NaOCl and its cytotoxicity did not change over time compared to other solutions.