Prevention of Enamel Softening by Rinsing with a Calcium Solution before Dental Erosion

Objectives: This in situ study aimed to evaluate whether rinsing with a calcium-containing solution prior to an erosive attack reduces the softening of enamel. Materials and Methods: A total of 240 bovine enamel samples with determined baseline surface microhardness (KHN) were allocated to 5 runs in which each of the 12 volunteers performed the following experiment: 4 enamel samples were inserted in a custom-made intraoral appliance and carried in the mouth (upper jaw) for 30 min before each volunteer either rinsed his mouth for 60 s with a fluoride- and stannous ion-containing dental erosion protection mouth rinse as positive control (run 1), milk (run 2), a solution prepared from a 500-mg calcium effervescent tablet dissolved in 100 mL (run 3) or 200 mL (run 4) water, or did not perform any rinsing with a test solution before the erosive attack (run 5, negative control). To simulate the erosive attack, volunteers rinsed their mouth with a commercial soft drink (Sprite Zero) for 60 s and afterwards with water to stop the erosive process. Finally, surface microhardness was measured again and hardness loss (ΔKHN) calculated. A mixed effect model was fitted to the data set to investigate whether the different runs showed differences with respect to ΔKHN. Results: No significant difference in softening of enamel (mean of ΔKHN; lower confidence level/upper confidence level) was observed between the negative control run 5 (50.7; 60.8/40.6), run 2 (50.7; 60.8/40.6), run 3 (38.7; 48.8/28.6) and run 4 (40.7; 50.8/30.6) (p > 0.05, respectively). Enamel softening in the positive control run 1 (25.4; 35.6/15.3) was significantly lower compared to the softening in run 5 (p < 0.001). No significant difference was observed between run 1 and run 3 (p = 0.09). Conclusion: Other than the fluoride- and stannous ion-containing dental erosion protection mouth rinse, none of the investigated calcium-containing solutions is able to significantly reduce erosion-induced softening of enamel.

Effects of medicinal plants on radiolabeling and biodistribution of diagnostic radiopharmaceuticals: A systematic review

Radiopharmaceuticals are drugs that contain radioisotopes used for diagnostic and therapeutic purposes. There are evidences that medicinal herbs and their constituents can modify the radiolabeling, biodistribution, and pharmacokinetics of radiopharmaceuticals through drug interaction. To have an overview of the effects and the underlying mechanisms of medicinal plants on the radiolabeling and bioavailability of radiopharmaceuticals, we conducted this study to summarize the current findings in this field. The scientific literature was systematically collected from databases and analyzed. Studies showed that medicinal plants and their constituents can alter radiolabeling and biodistribution via several mechanisms. Interactions with proteins in red blood cells at the same sites, chelating action of stannous and pertechnetate ions, antioxidant action impeding or decreasing stannous ion oxidation, direct oxidation of stannous ions, generation of reactive oxygen species (ROS) which oxidize stannous ions and damage induced in the cell membrane. Most the medicinal plants can decrease the radioactivity of radiopharmaceuticals, but some of them like Peumus boldus, Punica granatum, Nectandra membranacea, Mentha crispa, Rosmarinus officinalis and derivatives such as eugenol and epigallocatechin gallate have increasing effects. In addition, altering feature in some of them is tissue dependent.

Mechanistic Observations on the Role of the Stannous Ion in Caries Lesion De- and Remineralization

Two mechanistic, laboratory, factorial design studies were conducted to investigate the effect of the stannous ion (Sn2+) in the absence or presence of fluoride on caries lesion de- and remineralization. Study I was concerned with determining changes in mineral distribution of subsurface lesions, whereas study II investigated changes in surface hardness of surface-softened lesions as a function of pH. Study I showed that Sn2+ modulates the effects of fluoride by preventing lamination. Study II revealed that the effect of Sn2+ on rehardening is pH dependent. Neither study demonstrated synergy between Sn2+ and fluoride, yet interactions were observed. Sn2+ does interfere with remineralization to some extent although it provided acid resistance. The role of Sn2+ in the caries process is complex.

The Stannous Complex of Succinimide as Multifuctional Additive for Lubricating Oils

The excellent performance of dispersion makes poly-isobutene succinimide widely used in engine's lubricating oils. But this additive has no anti-oxidation ability, anti-friction and anti-wear behaviors. In engine’s oil, it must be used with antioxidants, extreme-pressure additives and detergents. Here the authors suggested that by metallizing the succnimide, many useful lubricating chemical properties would be affiliated to this additive. The nitrogen radicals of succinimide can combine with metal ions, such as transition metal ions, forming coordination compounds. In this article, the stannous ion was chosen as coordination ion that has stronger reducibility. The stannous chloride reacts with succinimide at 170°C, forming a new complex. The lubrication chemical experiments have shown that such complex has better performances as lubricating oil's additive, for example excellent dispersing ability, higher extreme-pressure performance, and good reducibility. All the appended abilities of poly-isobutene succinimide are ascribed to the introduction of stannous ion.

Effect of the extract of Ricinus communis L. on the osmotic fragility, labeling of red blood cells with Technetium-99m and morphology of the cells

The aim of this study was to evaluate the influence of the proteic extract of R. communis on the cell physiology by the osmotic fragility, labeling of the blood elements with the 99mTc and cell morphology. To evaluate the osmotic fragility, the blood samples of the Wistar rats were incubated with the concentrations of R. communis and with the solutions of NaCl (0.4; 0.7; 0.9%). In the labeling of the blood elements procedure, the rat blood was treated with a solution of Tc-99m and TCA at 5%, determining the rate of radioactivity (%ATI) in the plasma (P) and in the red blood cells (RBC). The soluble and insoluble fractions of the plasma were also evaluated. The cells morphology submitted to the extract was evaluated by the optical microscopy (x40). The results indicated that the rate of the hemolysis increased in the presence of 0.125 mg/mL of the extract. There was a decay of 49.69% in the rate of ATI in the insoluble fraction of the cells, with the morphological alterations in the red blood cells. These results suggested that the extract changed the capability of binding of the red blood cells due to the stannous ion oxidation, modifying the cells structure.