Effect of sodium metabisulfite gel on the bond strength of dentin of bleached teeth

Sodium Metabisulfite in Food and Biological Samples: A Rapid and Ultra-Sensitive Electrochemical Detection Method

The primary benefit of using sulfites as a food additive is their antimicrobial and antioxidant properties, which stop fungi and bacteria from growing in a variety of foods. The application of analytical methods is necessary to ensure food quality control related to the presence of sulfites in a variety of foods. For the detection of sodium metabisulfite in food and urine samples, two sensors based on reduced graphene oxide doped with Pd paste and modified with 5,10,15,20-tetraphenyl-21H,23H-porphyrin and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin were proposed. The new sensors were evaluated and characterized using square wave voltammetry. The response characteristics showed that the detection limits for the sensors were 3.0 × 10^-12 mol L^-1 for TPP/rGO@Pd0 based sensors and 3.0 × 10^-11 mol L^-1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors while the quantification limits were 1.0 × 10^-11 mol L^-1 for TPP/rGO@Pd0 based sensors and 1.0 × 10^-10 mol L^-1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors. The sensors can be used to determine sodium metabisulfite in a concentration range between 1.0 × 10^-11 and 1.0 × 10^-7 mol L^-1 for TPP/rGO@Pd0 based sensors and between 1.0 × 10^-10 mol L^-1 and 1.0 × 10^-6 mol L^-1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors. A comparison between the proposed methods' results and other analytical applications is also presented.

Sodium metabisulfite as a cytotoxic food additive induces apoptosis in HFFF2 cells

Sodium metabisulfite (SMB), an antioxidant agent, is extensively used as a preservative in food industry. The current study was aimed to clarify its potential toxic effects on human fetal foreskin fibroblasts (HFFF2) cells, in vitro. Subsequently, MTT results illustrated that exposure to SMB significantly (p < 0.0001) decreased HFFF2 cell viability in a dose-dependent manner, and the concentration of 25 μM reduced cell survival rates to 50% as the half-maximal inhibitory concentration of SMB. It was further shown that SMB exerted this cytotoxic effect on HFFF2 cells through apoptosis induction. qRT-PCR and western blotting results showed that treatment of HFFF2 cells with this food additive led to significant upregulation of Bax, caspase 8, and caspase 9 pro-apoptotic genes and downregulation of Bcl-2 expression as a pro-survival agent. Furthermore, SMB remarkably increased caspase 3 levels and promoted its activation through cleavage in treated cells. Besides, exposure to SMB increased ROS levels and activated autophagy in treated cells, which are considered as the other indicators for cell damage. Taken together, our findings suggested that SMB could exert remarkable toxic effects on human normal cells through multiple mechanisms, including apoptosis activation, and its widespread usage in food safety should be reconsidered.

Bleaching Stained Arrested Caries Lesions: In vivo Clinical Study

Objective  Conservative approaches to esthetically treat stained arrested caries lesions (s-ACLs) have not been explored in clinical studies. This study aims to investigate the efficacy of in-office dental bleaching agent, as a conservative approach, to esthetically treat s-ACLs.

Materials and Methods  Twelve patients ( n = 46) presented with s-ACLs were treated with 40% hydrogen peroxide (in-office bleaching protocol; 20 minutes × 3). Color values were measured using a spectrophotometer (CIE L*a*b*), aided with digital photography to assess visual color change clinically. Measurements were taken for each specimen at baseline and immediately after bleaching.

Statistical Analysis  The color change calculated before and after bleaching for each dental substrate was analyzed using paired t -test (α = 0.05).

Results  The bleached s-ACLs had a significant increase in L * values ( p < 0.001), and a significant decrease in both a * ( p = 0.001) and b * ( p = 0.007) values, indicating lighter color improvement (bleaching efficacy). The baseline mean of L *, a *, and b * values were 61.5, 2, and 15.4, respectively, and after bleaching were 67.7, 1.4, and 13.3, respectively, with a mean increase in ∆ E of >7.9, which resulted in a visible clinical stain improvement as orange/light brown stains were removed completely, while gray/black stains improved to a lesser extent.

Conclusion  Significant color improvement was observed when the in-office bleaching protocol (40% hydrogen peroxide) was used in orange/brown s-ACLs. However, it showed lesser improvement in gray/black s-ACLs.