https://www.selleckchem.com/products/gdc-0068.html  Despite the agreement that there is no longer any indication for arsenic use in modern endodontics, some concerns are surfacing about the minute amount of arsenic trioxide (As O ) released from Portland cement-based materials. The present study investigated the effect of different concentrations of As O on rat pulpal cells and the efficacy of -acetylcysteine (NAC) in preventing As O -mediated toxicity.  Cytotoxicities of 50, 10, or 5 µm As O and the effect of cells co-treatment with 50 µm As O and 5,000 µm NAC or 500 µm NAC were tested at 24 hours or 3 days. Cell viability was assessed by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and cellular morphological changes were observed under phase contrast microscope.  Two-way analysis of variance with Tukey's post-hoc test was used to evaluate differences between the groups (α = 0.05).  At both exposure times, 50 µm As O resulted in lower optical density (OD) values when compared with 10 or 5 µm As he proliferative effect induced by low As O concentrations should be interpreted with caution. NAC did not prevent As O -mediated toxicity; however, it demonstrated potential for ameliorating this toxicity.  As2O3 displayed a hormetic effect on pulpal cells; however, the proliferative effect induced by low As2O3 concentrations should be interpreted with caution. NAC did not prevent As2O3-mediated toxicity; however, it demonstrated potential for ameliorating this toxicity.  The purpose of this study was to evaluate the effect of bacterial cellulose nanocrystals (BCNCs) on the mechanical properties of resin-modified glass ionomer cements (RMGICs) including compressive strength (CS), diametral tensile strength (DTS), and modulus of elasticity ( ).  BCNCs were incorporated into RMGIC at various concentrations (0.3, 0.5, and 1 wt%). Unmodified RMGIC was used as the control group. The specimens were stored in distilled water at 37°C for 24 hour