Clinical Efficacy of Mouthwashes with Potassium Salts in the Treatment of Dentinal Hypersensitivity: A Systematic Review and Meta-analysis.

AIM: This systematic review and meta-analysis evaluated whether the home use of mouthwashes containing potassium salts is effective in reducing and controlling dentin hypersensitivity (DH). METHODS AND MATERIALS: This study is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist and was registered in PROSPERO (CRD42021228410). Randomized clinical trials evaluating the use of mouthwashes containing potassium salt for daily household mouthwash for at least four weeks to reduce DH compared with a control mouthwash were selected, with no limitation on year of publication. Electronic research was carried out in PubMed/MEDLINE, Scopus, Web of Science, and Cochrane Library by two independent researchers. One hundred thirty-three articles were obtained, and nine were selected according to the inclusion criteria. RESULTS: The selected studies evaluated DH through tests of sensitivity to tactile and evaporative stimuli and showed that, for the tactile stimulus, there were no baseline differences between groups (p=0.12; mean difference: -0.33; confidence intervals [CI]: -0.73 to 0.08). However, there were significant differences after two weeks of use (p=0.00001; mean difference: 4.67; CI: 4.53 to 4.81), after four weeks (p=0.00001; mean difference: 13.29; CI: 13.03 to 13.55), and after eight weeks (p=0.00001; mean difference: 8.88; CI: 5.73 to 12.02) favoring the experimental group. The results of the evaporative test showed no differences in the baseline assessment between the two groups (p=0.50; mean difference: -0.02; CI: -0.09 to 0.04), but after four weeks (p=0.00001; mean difference: -0.32; CI: -0.44 to -0.20), and eight weeks of use (p=0.00001; mean difference: -0.42; CI: -0.57 to -0.27) there were differences favoring the experimental group. The incidence of side effects showed no differences between the two groups (p=0.89; mean difference: 1.03; CI: 0.67 to 1.58). CONCLUSION: The daily use of mouthwashes containing potassium salt is effective in the treatment of dentinal hypersensitivity, as a complementary step to brushing at least twice a day for two weeks, four weeks, and up to eight weeks, without presenting side effects.

Light-enhanced free radical formation and trypanocidal action of gentian violet (crystal violet).

Transmission of Chagas' disease by transfusion of blood containing Trypanosoma cruzi has often been reported, and gentian violet, a triarylmethane dye, is widely used by blood banks in attempts to eliminate such transmission. In a study of intact trypanosomes, gentian violet was found to undergo a one-electron reduction to produce a carbon-centered free radical as demonstrated by electron spin resonance spectroscopy. Either reduced nicotinamide adenine dinucleotide or the reduced dinucleotide phosphate could serve as a source of reducing equivalents for the production of this free radical by homogenates of Trypanosoma cruzi. The formation of this free radical, and the trypanocidal action of gentian violet, were enhanced by light. The enhanced free radical formation may be the basic cause of the selective toxicity of gentian violet to Trypanosoma cruzi.

Generation of free radicals from metronidazole and other nitroimidazoles by Tritrichomonas foetus.

Metronidazole, ronidazole, secnidazole, benznidazole, and misonidazole are reduced by intact Tritrichomonas foetus cells to nitro anion radicals that can be detected by electron spin resonance spectroscopy. This activity appears to be related to the cellular content of reducing substrates, since nitro anion radical formation is stimulated in the presence of glucose and pyruvate. The nitro anion radicals could not be detected under aerobic conditions. Anaerobic homogenates of T. foetus also reduce metronidazole to the nitro anion radical when pyruvate, NADH, or NADPH is added as the ultimate source of reducing equivalents. Free radical formation may be the basic cause of nitroimidazole toxicity in trichomonads.

Generation of free radicals induced by nifurtimox in mammalian tissues.

Nifurtimox is reduced by rat liver microsomes to a nitro anion-free radical as indicated by ESR spectroscopy. This subcellular fraction gives a steady state radical concentration which is proportional to the square root of the protein concentration, suggesting that the nifurtimox anion radical is a necessary intermediate in the reduction and that the radical decays through a nonenzymatic second order process. The steady state concentration of the anion radical in the microsomal system is not decreased by superoxide dismutase or catalase, thus indicating that neither the superoxide anion nor hydrogen peroxide is an intermediary in the generation of the anion radical. The steady state concentration of the anion radical in the microsomal system is also not altered in the presence of metyrapone or CO and is decreased in the presence of NADP+ and p-chloromercuribenzoate. This observation suggests that the formation of nifurtimox anion radical is mediated through NADPH-cytochrome P-450 (c) reductase and not by the cytochrome P-450 system. In accordance with this interpretation, a model system consisting of NADPH and FMN-reduced nifurtimox to the nitro anion-free radical. Nifurtimox anion radical generation is significantly stimulated by rat brain and testes homogenates. The enhanced free radical formation may be the basic cause of nifurtimox toxicity in mammals.

Generation of free radicals from phenazine methosulfate in Trypanosoma cruzi epimastigotes.

A significant growth inhibition of Trypanosoma cruzi epimastigotes by phenazine methosulfate (PMS) was observed in Warren's medium. This toxic activity could be related to the following parameters: a) formation of phenazinium free radical, b) generation of superoxide anion in intact cells incubated with PMS, and c) PMS also increased significantly the rate of O2- generation in epimastigotes mitochondrial and microsomal fractions using NADH as electron donor.