'Green' silver nanoparticles combined with tyrosol as potential oral antimicrobial therapy.

OBJECTIVES: This study aimed to evaluate silver nanoparticles (AgNPs) obtained by a 'green' route associated or not to tyrosol (TYR) against Streptococcus mutans and Candida albicans in planktonic and biofilms states. METHODS: AgNPs were obtained by a 'green' route using pomegranate extract. The minimum inhibitory concentration (MIC) against S. mutans and C. albicans was determined for AgNPs and TYR combined and alone, and fractional inhibitory concentration index (FICI) was calculated. Single biofilms of C. albicans and S. mutans were cultivated for 24 h and then treated with drugs alone or in combination for 24 h. RESULTS: AgNPs and TYR were effective against C. albicans and S. mutans considering planktonic cells alone and combined. The MIC values obtained for C. albicans was 312.5 µg/mL (AgNPs) and 50 mM (TYR) and for S. mutans was 78.1 µg/mL (AgNPs) and 90 mM (TYR). The combination of these antimicrobial agents was also effective against both microorganisms: 2.44 µg/mL/0.08 mM (AgNPs/TYR) for C. albicans and 39.05 µg/mL /1.25 mM (AgNPs/TYR) for S. mutans. However, synergism was observed only for C. albicans (FICI 0.008). When biofilm was evaluated, a reduction of 4.62 log10 was observed for S. mutans biofilm cells treated with AgNPs (p < 0.05, Tukey test). However, the addition of TYR to AgNPs did not improve their action against biofilm cells (p > 0.05). AgNPs combined with TYR demonstrated a synergistic effect against C. albicans biofilms. CONCLUSIONS: These findings suggest the potential use of AgNPs with or without TYR against C. albicans and S. mutans, important oral pathogens. CLINICAL SIGNIFICANCE: AgNPs obtained by a 'green' route combined or not with TYR can be an alternative to develop several types of oral antimicrobial therapies and biomaterials.

Study of the activity of Punica granatum-mediated silver nanoparticles against Candida albicans and Candida glabrata, alone or in combination with azoles or polyenes.

The continuous emergence of Candida strains resistant to currently used antifungals demands the development of new alternatives that could reduce the burden of candidiasis. In this work silver nanoparticles synthesized using a green route are efficiently used, alone or in combination with fluconazole, amphotericin B or nystatine, to inhibit growth of C. albicans and C. glabrata oral clinical strains, including in strains showing resistance to fluconazole. A potent inhibitory effect over biofilm formation prompted by the two Candida species was also observed, including in mature biofilm cells. These results foster the use of phytotherapeutics as effective treatments in oral candidiasis.

Fluoride toothpaste supplemented with sodium hexametaphosphate reduces enamel demineralization in vitro.

OBJECTIVE: The aim of this study was to evaluate the effect of fluoride dentifrices combined with sodium hexametaphosphate (HMP) on enamel demineralization in vitro. MATERIAL AND METHODS: Enamel bovine blocks were selected by initial surface hardness (SHi) and then divided into five experimental groups (n = 12): placebo (without fluoride and without HMP); 1100 ppm F (1100F); and 1100F associated with HMP at 0.5 % (1100HMP0.5%), 1 % (1100HMP1%), and 2 % of HMP (1100HMP2%). Blocks were submitted to five pH cycles (demineralizing/remineralizing solutions) at 37 °C. After pH cycling, final surface hardness (SHf), percentage of surface hardness loss (%SH), integrated differential hardness (ΔIH), integrated loss of subsurface hardness (ΔKHN), and enamel firmly bound fluoride (F) were determined. Data were submitted to one-way ANOVA, followed by Student-Newman-Keuls test (p < 0.05). RESULTS: Significant differences were observed among all groups regarding %SH and ΔKHN. 1100HMP1% promoted the lowest mineral loss among all groups (p < 0.001), and led to significantly lower demineralization in the deeper regions of the subsurface lesion when compared with the other HMP-containing toothpastes (p < 0.001). Significantly higher mineral loss was observed for 1100HMP2% when compared to the other fluoridated dentifrices, mainly in the outer part of the lesion (p < 0.001). Enamel F uptake was similar for 1100F and 1100HMP1% but significantly reduced for other HMP concentrations. CONCLUSION: The supplementation of a 1100-ppm F dentifrice with 1 % HMP promoted a higher inhibitory effect against enamel demineralization when compared to a dentifrice containing the same amount of fluoride in vitro. CLINICAL RELEVANCE: This dentifrice could potentially be indicated to patients at high risk of caries.

Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro.

The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite.

Effect of sodium trimetaphosphate on hydroxyapatite solubility: an in vitro study.

This study evaluated the effect of different concentrations of sodium trimetaphosphate (TMP) with and without fluoride (F) on the concentration of calcium (Ca), phosphorus (P) and F in hydroxyapatite (HA). Synthetic HA powder (0.15 g) was suspended (n=6) in solutions (75 mL) of TMP at 0%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 2.0%, 4.0%, 6.0%, 8.0% and 10% concentrations in the presence and absence of 100 ppm F and subjected to a pH-cycling process. The precipitates were filtrated, dried at 70° C for 24 h and ground onto a fine powder. The concentrations of F (KOH (CaF2) and HCl (FA) soluble), Ca (Arsenazo III), and P (molybdate method) in HA were determined. The Ca P, and Ca/P ratio data were subjected to Tukey's test and the F data were subjected to Student-Newman-Keuls test (p<0.05). The addition of TMP to the samples reduced F deposition to 98% (p<0.001). The groups containing 100 ppm F and 0.4% or 0.6% TMP exhibited a higher Ca concentration than the group containing only 100 ppm F (p<0.05). Furthermore, the HA treated with 0.2% and 0.4% TMP and 100 ppm F showed a higher Ca/P ratio than the other groups (p<0.001). In conclusion, TMP at 0.2%, 0.4% and 0.6% concentrations combined with F seemed to be able to precipitate HA with low solubility. However, especially at high concentrations, TMP interferes with F deposition on HA.

Effect of Sodium Trimetaphosphate on Hydroxyapatite Solubility: An In Vitro Study

This study evaluated the effect of different concentrations of sodium trimetaphosphate (TMP) with and without fluoride (F) on the concentration of calcium (Ca), phosphorus (P) and F in hydroxyapatite (HA). Synthetic HA powder (0.15 g) was suspended (n=6) in solutions (75 mL) of TMP at 0%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 2.0%, 4.0%, 6.0%, 8.0% and 10% concentrations in the presence and absence of 100 ppm F and subjected to a pH-cycling process. The precipitates were filtrated, dried at 70° C for 24 h and ground onto a fine powder. The concentrations of F (KOH (CaF2) and HCl (FA) soluble), Ca (Arsenazo III), and P (molybdate method) in HA were determined. The Ca P, and Ca/P ratio data were subjected to Tukey's test and the F data were subjected to Student-Newman-Keuls test (p<0.05). The addition of TMP to the samples reduced F deposition to 98% (p<0.001). The groups containing 100 ppm F and 0.4% or 0.6% TMP exhibited a higher Ca concentration than the group containing only 100 ppm F (p<0.05). Furthermore, the HA treated with 0.2% and 0.4% TMP and 100 ppm F showed a higher Ca/P ratio than the other groups (p<0.001). In conclusion, TMP at 0.2%, 0.4% and 0.6% concentrations combined with F seemed to be able to precipitate HA with low solubility. However, especially at high concentrations, TMP interferes with F deposition on HA.

Este estudo avaliou o efeito de diferentes concentrações de trimetafosfato de sódio (TMP) com e sem fluoreto (F) nas concentrações de cálcio (Ca), fósforo (P) e F na hidroxiapatita (HA). Pó de HA sintético (0,15 g) foi suspenso (n=6) em soluções (75 mL) de TMP com concentrações de 0%, 0,1%, 0,2%, 0,4%, 0,6%, 0,8%, 1,0%, 2,0%, 4,0%, 6,0%, 8,0% e 10% na presença ou na ausência de 100 ppm F e foram submetidas ao processo de ciclagem de pH. O precipitado foi filtrado seco a 70°C por 24 h e triturado em um pó fino. As concentrações de F (solúvel em KOH: CaF2, e em HCl: FA), Ca (Arsenazo III) e P (método do molibdato) foram determinadas na HA. Os dados de Ca, P e de proporção Ca/P foram submetidos ao teste de Tukey e os dados de F ao teste Student-Newman-Keuls (p<0,05). A adição de TMP reduziu a deposição de F em 98% (p<0,001). Os grupos contendo 100 ppm F e TMP 0,4% e 0,6% apresentaram maiores concentrações de Ca do que o grupo contendo somente 100 ppm F (p<0,05). Além disso, a HA tratada com 0,2% e 0,4% de TMP e 100 ppm F apresentou maiores proporções Ca/P em relação aos demais grupos (p<0,001). Em conclusão, TMP nas concentrações de 0,2%, 0,4% e 0,6% quando associado ao F é capaz de precipitar uma HA com menor solubilidade. Entretanto, especialmente em altas concentrações, TMP interfere com a deposição de F na HA.