Development of experimental HEMA-free three-step adhesive system.

To evaluate the influence of Bis-EMA 30 on the resin-to-dentin microtensile bond strength (microTBS) and structural reliability of the experimental three-step etch-and-rinse adhesive systems.Five experimental primers containing different dimethacrylate monomer concentrations (0, 10, 20, 40, 60 wt% of the Bis-EMA 30, P0.P60) added to acid monomer and solvents (ethanol/water), and a resin bond (Bis-GMA/TEGDMA, 50/50 wt%) were formulated. The adhesive system Scotchbond MultiPurpose (SBMP, 3M ESPE) was tested as commercial reference. Sixty bovine incisors were randomly separated into six groups, and their superficial coronal dentin was exposed. After acid etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was actively applied (30 s), followed by a mild air stream (10 s). The experimental adhesive resin was applied and light activated for 20 s. Resin composite restorations were incrementally built up. The restored teeth were stored in distilled water at 37 degrees C for 24 h, and then sectioned to obtain sticks with a cross-sectional area of approximately 0.5 mm(2), after which 24 specimens per group were subjected to the microTBS test. Data (MPa) were analyzed by One-way ANOVA, Tukey test (alpha=0.05) and Weibull analysis.The P40 group showed microTBS means similar to those of the control (SBMP), whereas both had statistically higher values when compared with the other groups (p0.001). Moreover, P40 showed higher structural reliability, represented by the high Weibull modulus and characteristic strength values. The lowest microTBS was observed in the P0, P10 and P20 groups, which also had low structural reliability.Bis-EMA 30 is a promising monomer to be considered as a substitute for HEMA in adhesive system compositions

Development and characterization of novel ZnO-loaded electrospun membranes for periodontal regeneration

OBJECTIVES: This study reports on the synthesis, materials characterization, antimicrobial capacity, and cytocompatibility of novel ZnO-loaded membranes for guided tissue/bone regeneration (GTR/GBR). METHODS: Poly(ɛ-caprolactone) (PCL) and PCL/gelatin (PCL/GEL) were dissolved in hexafluoropropanol and loaded with ZnO at distinct concentrations: 0 (control), 5, 15, and 30wt.%. Electrospinning was performed using optimized parameters and the fibers were characterized via scanning and transmission electron microscopies (SEM/TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), contact angle (CA), mechanical testing, antimicrobial activity against periodontopathogens, and cytotoxicity test using human dental pulp stem cells (hDPSCs). Data were analyzed using ANOVA and Tukey (α=5%). RESULTS: ZnO nanoparticles were successfully incorporated into the overall submicron fibers, which showed fairly good morphology and microstructure. Upon ZnO nanoparticles' incorporation, the PCL and PCL/GEL fibers became thicker and thinner, respectively. All GEL-containing membranes showed lower CA than the PCL-based membranes, which were highly hydrophobic. Overall, the mechanical properties of the membranes were reduced upon ZnO incorporation, except for PCL-based membranes containing ZnO at the 30wt.% concentration. The presence of GEL enhanced the stretching ability of membranes under wet conditions. All ZnO-containing membranes displayed antibacterial activity against the bacteria tested, which was generally more pronounced with increased ZnO content. All membranes synthesized in this study demonstrated satisfactory cytocompatibility, although the presence of 30wt.% ZnO led to decreased viability. SIGNIFICANCE: Collectively, this study suggests that PCL- and PCL/GEL-based membranes containing a low content of ZnO nanoparticles can potentially function as a biologically safe antimicrobial GTR/GBR membrane

Synthesis and characterization of CaO-loaded electrospun matrices for bone tissue engineering

Objectives To synthesize and characterize biodegradable polymer-based matrices loaded with CaO-nanoparticles for osteomyelitis treatment and bone tissue engineering. Materials and methods Poly(ε-caprolactone) (PCL) and PCL/gelatin (1:1, w/w) solutions containing CaO nanoparticles were electrospun into fibrous matrices. Scanning (SEM) and transmission (TEM) electron microscopy, Fourier Transformed Infrared (FTIR), Energy Dispersive X-ray Spectroscopy (EDS), contact angle (CA), tensile testing, and antibacterial activity (agar diffusion assay) against Staphylococcus aureus (S. aureus) were performed. Osteoprecursor cell (MC3T3-E1) response (i.e., viability and alkaline phosphatase expression/ALP) and infiltration into the matrices were evaluated. Results CaO nanoparticles were successfully incorporated into the fibers, with the median fiber diameter decreasing after CaO incorporation. The CA decreased with the 0addition of CaO, and the presence of gelatin made the matrix very hydrophilic (CA = 0°). Increasing CaO concentrations progressively reduced the mechanical properties (p≤0.030). CaO-loaded matrices did not display consistent antibacterial activity. MC3T3-E1 cell viability demonstrated the highest levels for CaO-loaded matrices containing gelatin after 7 days in culture. An increased ALP expression was consistently seen for PCL/CaO matrices when compared to PCL and gelatin-containing counterparts. Conclusions Despite inconsistent antibacterial activity, CaO nanoparticles can be effectively loaded into PCL or PCL/gelatin fibers without negatively affecting the overall performance of the matrices. More importantly, CaO incorporation enhanced cell viability as well as differentiation capacity, as demonstrated by an increased ALP expression. Clinical significance CaO-loaded electrospun matrices show potential for applications in bone tissue engineering

Evaluation of Selective Physicochemical and Biological Properties of Different Root Canal Sealers

Introduction: This in vitro study aimed to evaluate the chemical composition, water solubility, radiopacity, pH, electrical conductivity and cytotoxicity of four different root canal sealers. Methods and Materials: Four materials were tested including an epoxy resin-based sealer (AH-Plus), a calcium silicate-based sealer (MTA Fillapex), a calcium hydroxide-based sealer (Sealapex) and a zinc-oxide-eugenol-based sealer (Endofill). The materials were submitted to energy-dispersive x-ray microanalysis for elemental chemical composition. Solubility and radiopacity were evaluated according to ANSI/ADA. The pH and electrical conductivity were measured at different periods of time. L929 immortalized mouse fibroblast line were used for cytotoxicity evaluation. Statistical analyses were carried out using the ANOVA and Tukey’s test. Results: The main elements were found to be silicon and calcium in MTA Fillapex, calcium and bismuth in Sealapex, zirconium and tungsten in AH-Plus and zinc and bismuth in Endofill. Sealapex had the highest value for solubility (P<0.05), AH-Plus showed the highest radiopacity value (P<0.05) while MTA Fillapex had the highest pH and electrical conductivity values (P<0.05). AH-Plus showed the highest rate of cell viability (P<0.05). Conclusion: Based on the results of this in vitro study, it was possible to conclude that Endofill and Sealpex did not meet the requirements for water solubility. The tested sealers were alkaline and showed radiopacity in accordance with ANSI/ADA standards. AH-Plus showed to be less cytotoxic than other tested root canal sealers. Keywords: Biological Assay; Endodontics; Root Canal Filling Materials; Root Canal Obturatio

Evaluation of physical-mechanical properties, antibacterial effect, and cytotoxicity of temporary restorative materials

The objective of this study was to compare selective physical-mechanical properties, antibacterial effects and cytotoxicity of seven temporary restorative materials (TRM): five resin-based materials [Bioplic (B), Fill Magic Tempo (FM), Fermit inlay (F), Luxatemp LC (L) and Revotek LC (R)], and zinc oxide-eugenol cement (IRM) and glass ionomer cement (GIC) as the controls. Material and methods: The physical-mechanical properties were evaluated by determining microleakage (ML), ultimate tensile strength (UTS) and Shore D hardness (SDH). In addition, the polymerization rate (Pr-1), depth of cure (DC), water sorption and solubility (WS/SL) were evaluated. The antimicrobial effects of the materials were assessed by biofilm accumulation of Streptococcus mutans (BT) and the direct contact test (DCT) by exposure to Enterococcus faecalis for 1 and 24 h, and cytotoxicity by MTT assay. The data were analyzed by ANOVA or Kruskall-Wallis tests, and a complementary post-hoc method (p<0.05). Results: Group B, followed by FM and GIC had significantly lower percentages of microleakage in comparison with the other groups; Groups FM and L showed the highest WS, while Groups R and FM showed the significantly lowest SL values (p<0.05). Group R showed the statistically highest UTS mean and the lowest DC mean among all groups. Group F showed the lowest S. mutans biofilm accumulation (p=0.023). Only the Group L showed continued effect against E. faecalis after 1 h and 24 h in DCT. The L showed statistically lower viability cell when compared to the other groups. Conclusions: These findings suggest the antibacterial effect of the temporary materials Fill Magic and Bioplic against S. mutans, while Luxatemp showed in vitro inhibition of S. mutans biofilm accumulation and E. faecalis growth. Regarding the cell viability test, Luxatemp was the most cytotoxic and Fill Magic was shown to be the least cytotoxic

Development and characterization of a novel bulk-fill elastomeric temporary restorative composite

Objectives: This study investigated the physical and mechanical properties, antibacterial effect and biocompatibility of novel elastomeric temporary resin-based filling materials (TFMs) containing zinc methacrylate (ZM). Material and Methods: Experimental TFMs were prepared by mixing the zinc methacrylate with monomer, co-monomer, photoinitiator and fillers. A ZM concentration of 0 (control), 0.5% (Z0.5); 1% (Z1), 2% (Z2), or 5% (ZM5) wt% was added to the TFMs. Fermit-N (F) was used for comparison with the experimental material. Microleakage, water sorption/solubility, degree of conversion, depth of cure, ultimate tensile strength, and hardness were determined and compared. A modified direct contact test (DCT) with Enterococcus faecalis and a Streptococcus mutans' biofilm accumulation assay was carried out to evaluate the antimicrobial effect and cytotoxicity of the assay. Statistical comparisons were performed (α=5%). Results: The results showed that the physical and mechanical properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference and some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values. TFMs with ZM killed E. faecalis only after 1 h. Biofilm development of S. mutans was not affected by the inclusion of ZM in the experimental TFMs. Conclusions: The present findings suggest that the physical, mechanical and biological properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference. However, some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values

Physicochemical Properties of MTA and Portland Cement after Addition of Aloe Vera

Introduction: The aim of this in vitro study was to determine the liquid-powder ratio, setting time, solubility, dimensional change, pH, and radiopacity of white structural and non-structural Portland cement, ProRoot MTA and MTA Bio, associated with a 2% glycolic solution containing Aloe Vera, as vehicle. Methods and Materials: Five samples of each material were used for each test, according to the American National Standards Institute/American Dental Association (ANSI/ADA) specification No. 57. Statistical analyses were performed using ANOVA and Tukey’s test at 5% significance. When sample distribution was not normal, non-parametric analysis of variance and the Kruskal-Wallis test were used (α=0.05). Results: No statistical differences were found in liquid-powder ratios among the tested materials. ProRoot MTA showed the longest setting time. Dimensional change values were acceptable in all groups. Also, no significant differences were found in pH values and pH was alkaline in all samples throughout the experiment. Mean radiopacity results obtained for white Portland cements did not meet ANSI/ADA requirements, and were significantly lower than those obtained for MTA-based cements. Finally, Portland cements showed significantly higher mean solubility values compared to the other samples. Conclusion: The physicochemical properties of the tested materials in association with Aloe Vera were compatible with ANSI/ADA requirements, except for the white Portland cements, which failed to meet the radiopacity specification.Keywords: Aloe Vera; MTA; Physicochemical Properties; Portland Cemen

Evaluation of irradiance and radiant exposure on the polymerization and mechanical properties of a resin composite

The objective of the present study was to evaluate the effect of irradiance and radiant exposure on the chemical–mechanical properties of a resin composite. A micro-hybrid resin composite (Clearfil AP-X, Kuraray) was investigated under two different irradiances: low (300 mW/cm2) and high (800 mW/cm2) and radiant exposures: 8 and 16 J/cm2. Four groups, named Low 8 J/cm2, High 8 J/cm2, Low 16 J/cm2, and High 16 J/cm2 were tested, and their flexural strengths, elastic moduli, depths of cure, and degrees of conversion were evaluated. Data were analyzed using two-way ANOVA and Tukey’s test. A multiple linear regression model was used to correlate the irradiance and radiant exposure with dependent variables (α = 0.05). Irradiance and radiant exposure were found statistically significant for all dependent variables. The interaction between the factors was statistically significant only for the degree of conversion and elastic modulus. Group Low 16 J/cm2 exhibited a significantly superior performance in all the evaluated properties. Barring the degree of conversion, no significant differences were observed among the properties evaluated between the Low 8 J/cm2 and High 8 J/cm2 groups. The adjusted R2 values were high for the depth of cure and degree of conversion (0.58 and 0.96, respectively). Both irradiance and radiant exposure parameters play an important role in establishing the final properties of a micro-hybrid resin composite. Irradiance has a greater influence under higher radiant exposure

Resistencia de unión al cizallamiento de un adhesivo experimental con extracto de semillas de uva a esmalte humano post-blanqueado

El objetivo del presente trabajo fue evaluar el efecto de la incorporación de ascorbato de sodio y extracto de semillas de uva al primer de un sistema adhesivo experimental autoacondicionante de dos pasos, en la resistencia de unión inmediata a esmalte humano blanqueado. Se utilizaron 42 terceros molares de los que se obtuvieron 84 especímenes que se dividieron aleatoriamente en 2 grupos: la mitad de los especímenes no fue blanqueado, mientras que la otra mitad fue sometida a un procedimiento de blanqueamiento con peróxido de carbamida al 45% durante 30 minutos. Posteriormente, los especímenes fueron subdivididos en 3 grupos dependiendo del sistema adhesivo con el que fueron restaurados: adhesivo sin antioxidante, con ascorbato de sodio al 15%, y con extracto de semillas de uva al 10%. Se confeccionaron cilindros de resina compuesta que fueron sometidos a un ensayo de resistencia de unión al microcizallamiento. Se utilizó el programa SigmaPlot 12.0. Se realizó una prueba de ANOVA de dos vías para evaluar el efecto de las variables independientes en la RUM. Se utilizó un nivel de significancia de α=0.05. Los grupos con mayores valores de resistencia de unión al microcizallamiento fueron: no blanqueado sin antioxidante (34,67MPa ± 8,79), no blanqueado con extracto de semillas de uva (35,62MPa ± 12,03) y blanqueado sin antioxidante (29,48MPa ± 6,94), sin diferencia estadísticamente significativa entre ellos. Los grupos en los que se utilizó el adhesivo con ascorbato, tanto el que recibió blanqueamiento como el que no fue blanqueado, mostraron los valores más bajos de resistencia de unión al microcizallamiento. Ninguno de los antioxidantes mejoró la resistencia de unión al microcizallamiento (p<0,05). La incorporación de extracto de semillas de uva al adhesivo no afecta negativamente la resistencia de unión al microcizallamiento. Sin embargo, no es capaz de mejorar la adhesión luego del blanqueamiento. En el caso del ascorbato de sodio, su incorporación en el primer del sistema adhesivo experimental parece no ser efectiva