Influence of Surface Treatment on the Physical Properties and Biofilm Formation of Zirconia- Reinforced Lithium Silicate Ceramics: In Vitro Trial.

PURPOSE: To evaluate the performance of fully crystallized zirconia-reinforced lithium silicate (Celtra Duo, ZLS-CD), partially crystallized zirconia-reinforced lithium silicate (Vita Suprinity, ZLS-VS), and partially sintered lithium disilicate-based (IPS e.max CAD, LD) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging. MATERIAL AND METHODS: Samples of each glass-ceramic material were subjected to polishing with rubber cups (POL), glazing (GL), or no treatment (control: unpolished) and afterward aged with 18,000 thermal cycles (5.C to 55.C). The average roughness, 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated with atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and the flexural strength test (n = 10), respectively. Data were analyzed using two-way ANOVA and Tukey test (α = 5%). RESULTS: POL produced lower surface roughness than GL, and ZLS-CD presented higher roughness than LD (P < .05). Surfaces without polishing displayed higher roughness than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glass-ceramic material. Irrespective of the treatment, the contact angle was higher in the ZLS-CD group, and regardless of the material, there was higher biofilm formation and lower flexural strength of the unpolished compared to the POL or GL ceramics. CONCLUSIONS: POL promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the GL group. In general, ZLS-CD and ZLS-VS showed more similar behavior than LD, which makes ZLS glass-ceramic a good option for indirect restorations.

Efficacy of true cinnamon (Cinnamomum verum) leaf essential oil as a therapeutic alternative for Candida biofilm infections.

OBJECTIVES: The essential oil (EO) extracted from Cinnamomum verum leaves has been used as an antimicrobial agent for centuries. But its antifungal and antibiofilm efficacy is still not clearly studied. The objective of this research was to evaluate the in vitro antifungal and antibiofilm efficacy of C. verum leaf EO against C. albicans, C. tropicalis, and C. dubliniensis and the toxicity of EO using an in vitro model. MATERIALS AND METHODS: The effect of EO vapor was evaluated using a microatmosphere technique. CLSI microdilution assay was employed in determining the Minimum Inhibitory (MIC) and Fungicidal Concentrations (MFC). Killing time was determined using a standard protocol. The effect of EO on established biofilms was quantified and visualized using XTT and Scanning Electron Microscopy (SEM), respectively. Post-exposure intracellular changes were visualized using Transmission Electron Microscopy (TEM). The toxicological assessment was carried out with the Human Keratinocyte cell line. The chemical composition of EO was evaluated using Gas Chromatography-Mass Spectrometry (GC-MS). RESULTS: All test strains were susceptible to cinnamon oil vapor. EO exhibited MIC value 1.0 mg/ml and MFC value 2.0 mg/ml against test strains. The killing time of cinnamon oil was 6 hr. Minimum Biofilm Inhibitory Concentration (MBIC50) for established biofilms was <0.2 mg/ml for all test strains. SEM images exhibited cell wall damages, cellular shrinkages, and decreased hyphal formation of Candida. TEM indicated intracellular vacuolation, granulation, and cell wall damages. Cinnamon leaf oil caused no inhibition of HaCaT cells at any concentration tested. Eugenol was the abundant compound in cinnamon oil. CONCLUSION: C. verum EO is a potential alternative anti-Candida agent with minimal toxicity on the human host.

Antibiofilm and Anti-Candidal Activities of the Extract of the Marine Sponge Agelas dispar.

This study aimed to determine the antifungal and antibiofilm activities of Agelas dispar on biofilm-producing Candida species. The methanolic extract of A. dispar was obtained and the fraction Ag2 showed inhibitory activity for all 13 Candida strains tested, in concentrations ranging from 2.5 to 0.15625 mg/mL. Antifungal activity of fungicidal nature was seen between 5.0 and 0.3125 mg/mL of extract against the strains. All the strains were classified as biofilm producers. The methanolic extract Ag2 was tested at concentrations of 2.5 and 1.25 mg/mL for antibiofilm activity against the biofilm formation and maturation in all the strains of the genus Candida. Treated and untreated biofilm samples were selected for visualization using scanning electron microscopy (SEM). SEM allowed the visualization of the quantitative decrease in the microbial community, alterations of structural morphology, and destruction of both the formation and maturation of biofilms, at the cellular level. The mechanism of action of this fraction is suggested to be at the plasma membrane and/or cell wall alteration level. Therefore, the use of the methanolic extract of A. dispar may be a promising antifungal and antibiofilm therapeutic strategy against different species of the genus Candida.

Effect of Cinnamomum verum leaf essential oil on virulence factors of Candida species and determination of the in-vivo toxicity with Galleria mellonella model.

BACKGROUND: Essential oils (EO) extracted from Cinnamomum verum has been used as an antimicrobial agents for centuries. The effects of C. verum leaf oil against virulence of microorganisms is not well studied yet. OBJECTIVES: This study evaluates the effect of C. verum leaf oil against three virulence factors of Candida albicans, C. tropicalis and C. dubliniensis and its in-vivo toxicity. METHODS: Chemical composition of EO was determined using gas chromatography-mass spectrometry (GC-MS). Minimum inhibitory concentration (MIC) was determined using clinical and laboratory standards institute (CLSI) M27-A3 broth microdilution. Effect of EO on initial adhesion was quantified using XTT assay after allowing Candida cells to adhere to the polystyrene surface for 2 h. Biofilm formation of Candida in the presence of EO was quantified using XTT viability assay. Efficacy on reduction of germ tube formation was evaluated using standard protocol. Visualisation of biofilm formation and progression under the EO treatment were done using scanning electron microscope (SEM) and Time lapses microscope respectively. In-vivo toxicity of EO was determined using Galleria mellonella larvae. Chlorhexidine digluconate: positive control. RESULTS: Eugenol was the main compound of EO. MIC was 1.0 mg/mL. 50% reduction in initial adhesion was achieved by C. albicans, C. tropicalis and C. dubliniensis with 1.0, > 2.0 and 0.34 mg/mL respectively. 0.5 and 1.0 mg/mL significantly inhibit the germ tube formation. MBIC50 for forming biofilms were ≤ 0.35 mg/mL. 1.0 mg/mL prevent biofilm progression of Candida. SEM images exhibited cell wall damages, cellular shrinkages and decreased hyphal formation. No lethal effect was noted with in-vivo experiment model at any concentration tested. CONCLUSION: C. verum leaf oil acts against virulence factors of Candida and does not show any toxicity.