RESUMO
Introduction: Silver diamine fluoride (SDF) is a topical treatment for carious lesions and a primary preventative for newly exposed high-risk surfaces such as fissures and roots in the first molars. Using potassium iodide (KI) after applying SDF has been recommended as a way of reducing the severity of black staining, as well as preserving its antibacterial effect useful in deep caries. Objective: The objective of this research was to compare the antibacterial effect of SDF, with and without KI, on Streptococcus mutans (S. mutans) and dental biofilm. Methods: The antibacterial effects of SDF, KI, and the combination of both were measured using three different techniques (inhibition halo, minimum inhibitory effect [MIE], and colony-forming unit [CFU], testing). Results: The results were then subjected to statistical analysis. Analyzed by means of the Kruskal-Wallis statistical test, the inhibition halos yielded a value of P = 0.3309. Using the MIE test, only the SDF treatment produced an antibacterial effect, at 10%, compared to the KI group, with P = 0.001. Finally, the CFU test revealed a total absence of colonies for all three reagents. All three substances analyzed achieved total inhibition of S. mutans. SDF is effective even in its minimal commercial concentration. Its antibacterial capacity decreases with the addition of KI. Conclusions: The three substances analyzed at their maximum concentrations exhibited an antibacterial effect against S. mutans, resulting in total inhibition.
RESUMO
During Trypanosoma cruzi infection, oxidative stress is considered a contributing factor for dilated cardiomyopathy development. In this study, the effects of astaxanthin (ASTX) were evaluated as an alternative drug treatment for Chagas disease in a mouse model during the acute infection phase, given its anti-inflammatory, immunomodulating, and anti-oxidative properties. ASTX was tested in vitro in parasites grown axenically and in co-culture with Vero cells. In vivo tests were performed in BALB/c mice (4-6 weeks old) infected with Trypanosoma cruzi and supplemented with ASTX (10 mg/kg/day) and/or nifurtimox (NFMX; 100 mg/kg/day). Results show that ASTX has some detrimental effects on axenically cultured parasites, but not when cultured with mammalian cell monolayers. In vivo, ASTX did not have any therapeutic value against acute Trypanosoma cruzi infection, used either alone or in combination with NFMX. Infected animals treated with NFMX or ASTX/NFMX survived the experimental period (60 days), while infected animals treated only with ASTX died before day 30 post-infection. ASTX did not show any effect on the control of parasitemia; however, it was associated with an increment in focal heart lymphoplasmacytic infiltration, a reduced number of amastigote nests in cardiac tissue, and less hyperplasic spleen follicles when compared to control groups. Unexpectedly, ASTX showed a negative effect in infected animals co-treated with NFMX. An increment in parasitemia duration was observed, possibly due to ASTX blocking of free radicals, an anti-parasitic mechanism of NFMX. In conclusion, astaxanthin is not recommended during the acute phase of Chagas disease, either alone or in combination with nifurtimox.