'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.

Pomegranate extract in polyphosphate-fluoride mouthwash reduces enamel demineralization

OBJECTIVES

To evaluate the anti-demineralizing effect of a mouthwash comprising pomegranate peel extract (PPE 3%), sodium trimetaphosphate (TMP 0.3%), and fluoride (F 225 ppm) in an in situ study, and to assess its irritation potential in an ex vivo study.

METHODS

This double-blind crossover study was conducted in four phases with 7 days each. Twelve volunteers used palatal appliances containing enamel blocks, which were subjected to cariogenic challenges. The ETF formulation (PPE + TMP + F, pH 7.0), TF formulation (TMP + F, pH 7.0), deionized water (W, pH 7.0), and essential oil commercial mouthwash (CM, 220 ppm F, pH 4.3) were dropped onto the enamel twice daily. The percentage of surface hardness loss, integrated loss of subsurface hardness, calcium, phosphorus, and fluoride in enamel and biofilms were determined. In addition, alkali-soluble extracellular polysaccharide concentrations were analyzed in the biofilms. The irritation potential was evaluated using the hen's egg chorioallantoic membrane test through the vascular effect produced during 300-s of exposure.

RESULTS

ETF was the most efficacious in preventing demineralization. It also showed the highest concentrations of calcium and phosphorus in the enamel and in the biofilm, as well as the lowest amount of extracellular polysaccharides in the biofilm. In the eggs, ETF produced light reddening, whereas CM led to hyperemia and hemorrhage.

CONCLUSIONS

The addition of PPE to formulations containing TMP and F increased its anti-demineralizing property, and this formulation presented a lower irritation potential than the CM.

CLINICAL RELEVANCE

ETF can be a promising alternative alcohol-free mouthwash in patients at high risk of caries.

Pomegranate Extract Potentiates the Anti-Demineralizing, Anti-Biofilm, and Anti-Inflammatory Actions of Non-Alcoholic Mouthwash When Associated with Sodium-Fluoride Trimetaphosphate

This study investigated the anti-caries and anti-inflammatory effects of mouthwash formulations containing Punica granatum (pomegranate) peel extract (PPE), sodium-trimetaphosphate, and low concentrations of fluoride. PPE was characterized using high-performance liquid chromatography (ellagic acid and punicalagin). Total phenolics were quantified among formulations, and their stability was analyzed for 28 days. The formulation effects were evaluated as follows: (1) inorganic component concentration and reduced demineralization on bovine enamel blocks subjected to pH cycling; (2) anti-biofilm effect on dual-biofilms of Streptococcus mutans ATCC 25175 and Candida albicans ATCC 10231 treated for 1 and 10 min, respectively; and (3) cytotoxicity and production of inflammatory mediators (interleukin-6 and tumor necrosis factor-alpha). The formulation containing 3% PPE, 0.3% sodium-trimetaphosphate, and 225 ppm of fluoride resulted in a 34.5% surface hardness loss; a 13% (treated for 1 min) and 36% (treated for 10 min) biofilm reduction in S. mutans; a 26% (1 min) and 36% (10 min) biofilm reduction in C. albicans; absence of cytotoxicity; and anti-inflammatory activity confirmed by decreased interleukin-6 production in mouse macrophages. Thus, our results provide a promising prospect for the development of an alcohol-free commercial dental product with the health benefits of P. granatum that have been recognized for a millennium.

Green and Chemical Silver Nanoparticles and Pomegranate Formulations to Heal Infected Wounds in Diabetic Rats

Infected cutaneous ulcers from diabetic rats with Candida albicans and Streptococcus aureus were treated with spray formulations containing green silver nanoparticles (GS), chemical silver nanoparticles (CS), or pomegranate peel extract (PS). After wound development and infection, the treatments were performed twice per day for 14 days. The wound healing was analyzed on days 2, 7, and 14 through the determination of CFUs, inflammatory infiltrate, angiogenesis, fibroplasia, myeloperoxidase, and collagen determination. Expressive improvement in wound healing was noted using both silver nanoparticles for 7 days. All the treatments were superior to controls and promoted significant S. aureus reduction after 14 days. CS presented better anti-inflammatory results, and GS and CS the highest number of fibroblasts. Despite the techniques' limitations, GS and CS demonstrated considerable potential for managing infected wounds, especially considering no early strategies prior to the drugs, such as the debridement of these wounds, were included.

0270 Somnolence Profiles in Mice Submitted to Acute and Chronic Sleep Deprivation

Introduction

Sleepiness is a behavioral marker of homeostatic sleep regulation and is related to several negative outcomes with interindividual variation, which may amount to central sleep mechanisms. However, there is a lack of evidence linking progressive sleep need and sleepiness with factors of individual variability, which could be tested by acute and chronic sleep deprivation. Thus, the study objective was to investigate the development of sleepiness in sleep deprived mice.

Methods

C57BL/6J male mice (n=340) were distributed in 5 sleep deprivation groups, 5 sleep rebound groups and 10 control groups. Animals underwent acute total sleep deprivation for 3, 6, 9 or 12 hours or chronic sleep deprivation for 6 hours for 5 consecutive days. Sleep rebound groups had the opportunity to sleep for 1, 2, 3, 4 hours after acute sleep deprivation or 24 hours after chronic sleep deprivation. During the protocol, sleep attempts were counted as a sleepiness index. After euthanasia, blood was collected for corticosterone assessment.

Results

Using the average group sleep attempts, it was possible to differentiate between sleepy (mean&gt;group average) and resistant to sleepiness animals (mean&lt;group average). Frequency of resistant mice was 65%, 56%, 56% and 53% for 3, 6, 9 and 12 hours of acute sleep deprivation, respectively, and 74% in chronic sleep deprivation. 52% of the sleepiness variance might be explained by individual variation during chronic sleep deprivation and 68% of sleepiness variance during acute sleep deprivation was attributed to extended wakefulness. A normal corticosterone zenith was observed at the start of the dark phase, independent of sleep deprivation.

Conclusion

Different degrees of sleepiness in sleep deprived mice were verified. Sleep deprivation per se was the main factor explaining sleepiness during acute sleep deprivation whereas in chronic deprivation individual variation was more relevant.

Support

This work was financially supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (#2017/18455-5), Coordenação de Aperfeiçoamento de Pessoal Nível Superior (CAPES) - grant code 001, ConselhoNacional de Desenvolvimento Científico e Tecnológico (CNPq) (#169040/2017–8)and Associação Fundo de Incentivo à Pesquisa (AFIP).

0828 Descriptive Model of Sleep Quality in the Older Adults

Introduction

Poor sleep quality is a health condition that impacts the quality of life of the older population. In the literature, there are questions about which objective sleep parameters should be considered to describe precisely the definition of sleep quality. There is ongoing debate with this term usually being used in relation to subjective sleep perception. This study aimed to investigate which objective and subjective sleep parameters contribute to a measurement of sleep quality in older adults.

Methods

A cross-sectional study using a representative sample of adults from the city of São Paulo, Brazil was performed. We used a dataset from the 2015 Epidemiological Study of Sleep from the City of São Paulo (EPISONO), including only individuals aged 60 years or more. We used exploratory factor analysis and structural equation modelling to identify relevant variables to a descriptive model of sleep quality.

Results

A total of 152 older adults were included. The final model consists of two factors, objective sleep quality which comprises sleep efficiency, total sleep time and sleep latency, and poor sleep perception, constituted by scores in the Pittsburgh Sleep Quality Index and Insomnia Severity Index.

Conclusion

The results suggested that sleep quality had both an objective (sleep efficiency, total sleep time, latency of sleep onset) and subjective dimensions (subjective questionnaires). These results may be useful in the clinical scenario, serving as leads for a better understanding of the sleep quality in aging patients. Future studies may also benefit from this descriptive model to further researches other associations, such as sleep and pain in this population.

Support

The study was supported by Associação Fundo de Incentivo à Pesquisa (AFIP) and Coordenação de Aperfeiçoamento de Nível Superior (CAPES). ST and MLA received support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

Influence of Chlorhexidine Gluconate on the Immediate Bond Strength of a Universal Adhesive System on Dentine Subjected to Different Bonding Protocols: An In Vitro Pilot Study

PURPOSE

The aim of this in vitro study was to evaluate the influence of preapplication of 2% chlorhexidine gluconate on the immediate microtensile bond strength of a universal adhesive system on dentine subjected to different bonding protocols.

MATERIALS AND METHODS

Twenty human molars were used in this study, and the tooth surface was abraded to expose the dentine. The teeth were randomly divided into four groups according to the surface treatment (n = 5): SBU group: Single Bond Universal without acid etching; SBUPA group: 37% phosphoric acid + Single Bond Universal; SBUCG group: 2% chlorhexidine gluconate + Single Bond Universal; and SBUPACG group: 37% phosphoric acid + 2% chlorhexidine gluconate + Single Bond Universal. The microtensile bond strengths were measured using a microtensile tester 24 h after bonding. The bond strength data were subjected to analysis of variance (ANOVA) and Sheffé's least statistically significant difference test (α = 0.05).

RESULTS

No statistically significant differences between the analysed groups were observed (p > 0.05). However, conditioning with phosphoric acid without the action of the chlorhexidine gluconate group resulted in higher numerical values of bond strengths than that for the chlorhexidine gluconate without the acid conditioning group.

CONCLUSION

The preapplication of 2% chlorhexidine gluconate did not reduce the immediate bond strength of the Single Bond Universal adhesive system under different bonding protocols.

Sodium trimetaphosphate and hexametaphosphate impregnated with silver nanoparticles: characteristics and antimicrobial efficacy

This study aimed to synthesize and characterize materials containing silver nanoparticles (AgNP) with polyphosphates (sodium trimetaphosphate (TMP) or sodium hexametaphosphate (HMP), and evaluate their effect against Candida albicans and Streptococcus mutans. The minimum inhibitory concentration (MIC) was determined, which was followed by the quantification of the biofilm by counting colony-forming units (CFUs), the amount of metabolic activity, and the total biomass. The MICs revealed greater effectiveness of composites containing 10% Ag (TMP + Ag10% (T10) and HMP + Ag10% (H10)) against both microorganisms. It was observed that T10 and H10 reduced the formation of biofilms by 56-76% for C. albicans and by 52-94% for S. mutans for total biomass and metabolic activity. These composites promoted significant log reductions in the number of CFUs, between 0.45-1.43 log₁₀ for C. albicans and 2.88-3.71 log₁₀ for S. mutans (p < .001). These composites demonstrated significant antimicrobial activity, especially against S. mutans, and may be considered a potential alternative for new dental materials.

Biofilm formation by Candida albicans and Streptococcus mutans in the presence of farnesol: a quantitative evaluation

The aim of this study was to evaluate the effect of the QS molecule farnesol on single and mixed species biofilms formed by Candida albicans and Streptococcus mutans. The anti-biofilm effect of farnesol was assessed through total biomass quantification, counting of colony forming units (CFUs) and evaluation of metabolic activity. Biofilms were also analyzed by scanning electron microscopy (SEM). It was observed that farnesol reduced the formation of single and mixed biofilms, with significant reductions of 37% to 90% and 64% to 96%, respectively, for total biomass and metabolic activity. Regarding cell viability, farnesol treatment promoted significant log reductions in the number of CFUs, ie 1.3-4.2 log10 and 0.67-5.32 log10, respectively, for single and mixed species biofilms. SEM images confirmed these results, showing decreases in the number of cells in all biofilms. In conclusion, these findings highlight the role of farnesol as an alternative agent with the potential to reduce the formation of pathogenic biofilms.

Premature rupture of membranes before 28 weeks managed expectantly: maternal and perinatal outcomes in a developing country

This study aimed to assess outcomes of expectant management for early preterm premature rupture of membranes (PPROM). This retrospective cohort involved 66 women with PPROM <28 weeks managed in a single hospital (1999-2006). Main outcomes were chorioamnionitis, severe maternal morbidity (maternal sepsis, haemorrhage/blood transfusion, hysterectomy or admission to intensive care unit), maternal mortality, low birth weight, preterm birth, neonatal infection and perinatal mortality. Mean gestational ages at PPROM and delivery were 21.7 ± 4.2 and 28.4 ± 5.9 weeks, respectively. Chorioamnionitis was diagnosed in 47%; no cases of severe maternal morbidity or mortality occurred. Stillbirth rate was 25.7% and >80% of infants were delivered before 34 weeks. Neonatal infection was diagnosed in 42.9% of the 49 live-births. Overall survival rate was 57.6%. Expectant management of PPROM <28 weeks resulted in high rates of chorioamnionitis and preterm deliveries but in over half of the cases, a live infant was discharged home.