Cannabidiol-loaded microparticles embedded in a porous hydrogel matrix for biomedical applications.

In this study, poly (lactic-co-glycolic acid) (PLGA) microparticles loaded with cannabidiol (CBD) were synthesized (PLGA@CBD microparticles) and embedded up to 10 wt% in a chondroitin sulfate/polyvinyl alcohol hydrogel matrix. In vitro chemical, physical, and biological assays were carried out to validate the potential use of the modified hydrogels as biomaterials. The microparticles had spherical morphology and a narrow range of size distribution. CBD encapsulation efficiency was around 52%, loading was approximately 50%. Microparticle addition to the hydrogels caused minor changes in their morphology, FTIR and thermal analyses confirmed these changes. Swelling degree and total porosity were reduced in the presence of microparticles, but similar hydrophilic and degradation in phosphate buffer solution behaviors were observed by all hydrogels. Rupture force and maximum strain at rupture were higher in the modified hydrogels, whereas modulus of elasticity was similar across all materials. Viability of primary human dental pulp cells up to 21 days was generally not influenced by the addition of PLGA@CBD microparticles. The control hydrogel showed no antimicrobial activity against Staphylococcus aureus, whereas hydrogels with 5% and 10% PLGA@CBD microparticles showed inhibition zones. In conclusion, the PLGA@CBD microparticles were fabricated and successfully embedded in a hydrogel matrix. Despite the hydrophobic nature of CBD, the physicochemical and morphological properties were generally similar for the hydrogels with and without the CBD-loaded microparticles. The data reported in this study suggested that this original biomaterial loaded with CBD oil has characteristics that could enable it to be used as a scaffold for tissue/cellular regeneration.

Development of Lead-Free Radiation Shielding Material Utilizing Barium Sulfate and Magnesium Oxide as Fillers in Addition Cure Liquid Silicone Rubber.

The radiological protection has the purpose of safeguarding the physical well-being of the user, preventing exposure to detrimental levels of ionizing radiation. This study introduces a novel, cost-effective category of lead-free elastomeric material designed for radiation shielding. The filler compounds utilized are notably lighter than conventional lead-based materials, enhancing user ergonomics during application. They comprise of a blend of barium sulfate combined or not with magnesium oxide with addition-cure liquid silicone rubber. To ensure the effectiveness of the radiation shielding, X-ray transmission measurements were performed for the different thicknesses of the materials and the results compared with Monte Carlo simulations. Additionally, the physical properties of the new materials, such as density, homogeneity, tensile strength, viscosity, and wettability, were also evaluated. The findings indicate that both materials fulfill the requirement for application in radiation protection garments.

Photocrosslinkable methacrylated gelatin hydrogel as a cell-friendly injectable delivery system for chlorhexidine in regenerative endodontics.

OBJECTIVES: This work sought to formulate photocrosslinkable chlorhexidine (CHX)-laden methacrylated gelatin (CHX/GelMA) hydrogels with broad spectrum of action against endodontic pathogens as a clinically viable cell-friendly disinfection therapy prior to regenerative endodontics procedures. METHODS: CHX/GelMA hydrogel formulations were successfully synthesized using CHX concentrations between 0.12 % and 5 % w/v. Hydrogel microstructure was evaluated by scanning electron microscopy (SEM). Swelling and enzymatic degradation were assessed to determine microenvironmental effects. Compression test was performed to investigate the influence of CHX incorporation on the hydrogels' biomechanics. The antimicrobial and anti-biofilm potential of the formulated hydrogels were assessed using agar diffusion assays and a microcosms biofilm model, respectively. The cytocompatibility was evaluated by exposing stem cells from human exfoliated deciduous teeth (SHEDs) to hydrogel extracts (i.e., leachable byproducts obtained from overtime hydrogel incubation in phosphate buffer saline). The data were analyzed using One- and Two-way ANOVA and Tukey's test (α = 0.05). RESULTS: CHX/GelMA hydrogels were effectively prepared. NMR spectroscopy confirmed the incorporation of CHX into GelMA. The addition of CHX did not change the micromorphology (pore size) nor the swelling profile (p > 0.05). CHX incorporation reduced the degradation rate of the hydrogels (p < 0.001); whereas, it contributed to increased compressive modulus (p < 0.05). Regarding the antimicrobial properties, the incorporation of CHX showed a statistically significant decrease in the number of bacteria colonies at 0.12 % and 0.5 % concentration (p < 0.001) and completely inhibited the growth of biofilm at concentration levels 1 %, 2 %, and 5 %. Meanwhile, the addition of CHX, regardless of the concentration, did not lead to cell toxicity, as cell viability values were above 70 %. SIGNIFICANCE: The addition of CHX into GelMA showed significant antimicrobial action against the pathogens tested, even at low concentrations, with the potential to be used as a cell-friendly injectable drug delivery system for root canal disinfection prior to regenerative endodontics.

Effect of Dental Course Cycle on Anatomical Knowledge and Dental Carving Ability of Dental Students.

This study assessed the effect of the course cycle on theoretical knowledge of dental morphology and the dental carving ability of dental students. Thirty-two dental students from the third semester (initial cycle) and 30 students from the eighth and tenth semesters of the dental course (end cycle) had their theoretical knowledge on dental morphology assessed using a questionnaire with ten closed questions. Their dental carving ability was also assessed using wax carvings in macro models of plaster (for the third [S3] and eight [S8] semesters) and natural-sized artificial teeth (for the tenth [S10] semester). The teeth chosen for the dental carving activity were #16 and #47. The scores were statistically analyzed using the t-test, Kruskal-Wallis test, and Mann-Whitney test (α = 0.05). Students from the initial cycle presented better theoretical knowledge than the other groups did (P < 0.007). No significant differences in carving score were found between the initial and end cycles (P > 0.05), although S10 students obtained a higher score for teeth #16 and #47 (P < 0.05). Natural-sized artificial teeth received a higher evaluation score in dental carvings than the macro models (P < 0.001). Within the limits of this study, it was possible to conclude that students from the initial cycle (S3) presented higher theoretical knowledge, whereas no difference in carving ability was observed between the initial and end cycles. The tenth semester (S10) students performed dental carvings with better quality. Furthermore, carvings in natural-sized artificial teeth presented better quality compared with the macro models.

Physicomechanical, optical, and antifungal properties of polymethyl methacrylate modified with metal methacrylate monomers.

STATEMENT OF PROBLEM: The high recurrence rates of denture stomatitis may be associated with the resistance of biofilms to therapeutics. Therefore, methods that provide biomaterials with antifungal properties are an attractive solution to improving microbial control. PURPOSE: The purpose of this in vitro study was to modify conventional polymethyl methacrylate (PMMA) through the incorporation of metal methacrylate monomers and to evaluate the physicomechanical and optical properties and antifungal activity of the modified materials. MATERIAL AND METHODS: Experimental denture base acrylic resins were fabricated through the addition of zirconium methacrylate (ZM), tin methacrylate (TM), and di-n-butyldimethacrylate-tin (DNBMT) to the liquid of a commercially available denture base PMMA resin. Unmodified PMMA resin was used as the control. The degree of conversion of the materials was tested through Fourier transform infrared spectroscopy (n=3). A digital spectrophotometer was used to assess the color change of the modified materials (n=8). Differences in Knoop hardness and roughness between experimental groups were also evaluated (n=8). A biofilm accumulation test with Candida albicans (ATCC 62342) (n=4) was performed for 5 days in Sabouraud broth culture supplemented with 10% sucrose. Data were subjected to analysis of variance and the post hoc Tukey honestly significant difference test (α=.05). RESULTS: The degree of conversion and color-change values of the experimental materials were statistically similar to those of the control (P=.593). The incorporation of DNBMT significantly increased the hardness of the modified material (P=.014). The ZM, TM, and DNBMT groups had higher antifungal activity against C. albicans (P=.001) and lower roughness than the control group (control 0.65 ±0.05 µm; ZM 0.34 ±0.09 µm, TM 0.34 ±0.11 µm, and DNBMT 0.41 ±0.08 µm). CONCLUSIONS: The metal-containing methacrylate monomers provided antifungal action to the modified materials without affecting the physicomechanical or optical properties of the denture base resin. ZM, TM, and DNBMT are potential reactive agents for the fabrication of PMMA denture base resins with antifungal properties.

Educational Interventions to Improve Dental Anatomy Carving Ability of Dental Students: A Systematic Review.

This systematic review aimed to identify the level of impact of educational strategies for teaching tooth carving on the carving ability of undergraduate dental students. The PubMed-NCBI, Cochrane-CENTRAL, LILACS, Ibecs, BBO, Web of Science, and Scopus databases were searched in May 2019, for randomized controlled trials (RCTs) and two-arm non-randomized studies of interventions (NRSI) addressing educational interventions toward the dental carving of undergraduate students. Studies from the year 2000 until the search date, written in English, Portuguese, and Spanish were included. Study screening and data extraction were performed in duplicate and blinded. The data were presented narratively, considering the dental carving ability of students the primary outcome. The risk of bias was assessed using the RoB tool 2.0 and ROBINS-I, and the level of evidence was determined with GRADE. Of 3,574 studies, 6 were included, with 3 RCTs and 3 NRSIs. Very low level of evidence was provided from the NRSIs that flipped classroom (1 study; n = 140) and a student-driven revised module (1 study; n = 264) improved the carving ability of students. Additionally, there was moderate evidence of online complementary material (1 RCT; n = 30) and reinforcement class improving the carving ability of students (1 RCT; n = 29). The replacement of traditional classes by an instructional DVD (1 RCT; n = 73) and assessment of carving projects through digital systems (1 NRSI; n = 79) did not enhance the carving ability of students. Study design, risk of bias, and imprecision downgraded the level of evidence. There was a very low to moderate evidence on the effectiveness of student-driven educational approaches and complementary classes of dental anatomy in improving the dental carving ability of students.

Development and properties of endodontic resin sealers with natural oils.

OBJECTIVES: To synthesize and evaluate the physicochemical, antimicrobial, and cytocompatibility properties of experimental resin-based endodontic sealers containing butia or copaiba natural oils. METHODS: Experimental groups contained butia (Butia capitata) at 0.5 % (B0.5), 1 % (B1), 2 % (B2), and copaiba (Copaifera spp.) at 0.5 % (C0.5), 1 % (C1), and 2 % (C2). The control group contained no added oils (experimental material, EM) and the commercial group was a methacrylate-based resin material (RealSeal™, SybronEndo Corporation, Orange, CA, USA). Degree of conversion, film thickness, setting time, flow, water sorption and solubility, and radiopacity were measured. Meanwhile, antimicrobial (modified direct contact test) and cytotoxicity assays of the experimental groups and controls were performed. One-way ANOVA was used to determine the effect of the independent variable (material) on the degree of conversion, film thickness, radiopacity, flow, setting time, water sorption and solubility, and cytotoxicity. For antimicrobial assays, data were analyzed using two-way ANOVA and Sidák's test. RESULTS: The experimental groups containing natural oils showed higher values of degree of conversion, and lowest water sorption and solubility. EM, B0.5, B1, B2, and RS showed similar film thicknesses. The flow values were statistically similar in all groups. The experimental groups showed adequate cell compatibility. Copaiba oil at 2% increased the antimicrobial effect after 1 and 24 h (p < 0.05). The incorporation of butia or copaiba resulted in a slight modification in some physicochemical properties of the experimental resin sealers. CONCLUSION: Novel resin sealers containing natural oils are a promising alternative for endodontics, because of their good physicochemical properties, antimicrobial effects, and cytocompatibility when compared to a commercially available sealer. CLINICAL SIGNIFICANCE: Endodontic sealers containing butia or copaiba had satisfactory cytocompatibility, antimicrobial effects, and adequate physicochemical properties.

Diversity, frequency and antifungal resistance of Candida species in patients with type 2 diabetes mellitus.

OBJECTIVE: To determine number, species of Candida and Candida resistance to antifungal therapy according to the metabolic control state and the associated salivary changes in patients with type 2 diabetes mellitus (DM2). MATERIALS AND METHODS: Samples of non-stimulated saliva were collected from 52 patients with DM2. Salivary pH was measured and cultured on Sabouraud glucose agar and the values of CFU/ml were calculated. The species were presumptively identified using CHROMagar Candida® plates, and identification was confirmed by polymerase chain reaction (PCR). C. albicans isolates were cultured on SGA tetracycline agar with nystatin and fluconazole diffusion disks to measure susceptibility. RESULTS: Sixty six percent of the yeasts isolated were Candida albicans, followed by C. glabrata (20.7%). In patients with decompensated DM2, there was an inverse association between HbA1c value and salivary pH. At higher levels of salivary acidification, a greater diversity and quantity of yeasts of the genus Candida were observed. With nystatin, higher inhibition was observed at lower pH. CONCLUSIONS: The antifungal therapies could be more effective if it consider, qualitative salivary characteristics as pH, that could determine the susceptibility of species of Candida to at least to nystatin, which is the most used antifungal for treatment to oral candidiasis in patients with DM2.

Macroalgae Extracts From Antarctica Have Antimicrobial and Anticancer Potential.

Background: Macroalgae are sources of bioactive compounds due to the large number of secondary metabolites they synthesize. The Antarctica region is characterized by extreme weather conditions and abundant aggregations of macroalgae. However, current knowledge on their biodiversity and their potential for bio-prospecting is still fledging. This study evaluates the antimicrobial and cytotoxic activity of different extracts of four macroalgae (Cystosphaera jacquinotii, Iridaea cordata, Himantothallus grandifolius, and Pyropia endiviifolia) from the Antarctic region against cancer and non-cancer cell lines. Methods: The antimicrobial activity of macroalgae was evaluated by the broth microdilution method. Extracts were assessed against Staphylococcus aureus ATCC 19095, Enterococcus faecalis ATCC 4083, Escherichia coli ATCC29214, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 62342, and the clinical isolates from the human oral cavity, namely, C. albicans (3), C. parapsilosis, C. glabrata, C. lipolytica, and C. famata. Cytotoxicity against human epidermoid carcinoma (A-431) and mouse embryonic fibroblast (NIH/3T3) cell lines was evaluated with MTT colorimetric assay. Results: An ethyl acetate extract of H. grandifolius showed noticeable antifungal activity against all fungal strains tested, including fluconazole-resistant samples. Cytotoxicity investigation with a cancer cell line revealed that the ethyl acetate extract of I. cordata was highly cytotoxic against A-431 cancer cell line, increasing the inhibitory ratio to 91.1 and 95.6% after 24 and 48 h exposure, respectively, for a concentration of 500 µg mL-1. Most of the algal extracts tested showed little or no cytotoxicity against fibroblasts. Conclusion: Data suggest that macroalgae extracts from Antarctica may represent a source of therapeutic agents. HIGHLIGHTS Different macroalgae samples from Antarctica were collected and the lyophilized biomass of each macroalgae was extracted sequentially with different solventsThe antimicrobial and anticancer potential of macroalgae extracts were evaluatedEthyl acetate extract of H. grandifolius showed noticeable antifungal activity against all the fungal strains tested, including fluconazole-resistant samplesEthyl acetate extract of I. cordata was highly cytotoxic against the A-431 cancer cell lineMost of the algal extracts tested showed little or no cytotoxicity against normal cell lines.

Optimizing quality of dental carving by preclinical dental students through anatomy theory reinforcement.

Knowledge of dental anatomy is of great importance in the practice of dentistry, especially in oral rehabilitation, because without this knowledge, professional practice is not possible. Dental carving plays a major role in training dental students as it develops their manual dexterity. This randomized controlled trial aimed to evaluate the influence of didactic-theoretical reinforcement on the theoretical and practical knowledge of dental anatomy of preclinical students by examining the quality of the anatomical restorations performed by these students before and after a didactic-theoretical reinforcement. For the evaluation of theoretical knowledge, a questionnaire with closed questions about dental anatomy was used. To evaluate the effect of didactic reinforcement on dental carvings, two groups of 15 preclinical students were assessed. Experimental group (G1) received a three-hour theoretical tutoring on dental anatomy, while the control group (G2) did not. The dental carving scores obtained by the two different groups were compared using Student's t-test. Cohen's d was used to estimate the effect sizes between groups. The frequency of correct answers given for each theoretical knowledge question was compared in each group using Fisher's exact test. T-test was also used to compare the means of the two groups' final scores of theoretical evaluations. To compare these final scores obtained in both carving and theoretical tests, a principal component analysis was performed with different items assessed in each test to obtain factor loading scores and a final weighted score, where factor loadings were considered for each item. Weighted scores were compared using t-test. Also, scores obtained during the head and neck course were assessed and compared using t-test. Spearman's correlation test was used to assess the correlation between scores obtained prior to the anatomy course and scores obtained in the dental carving exercise. The theoretical evaluation revealed no significant difference between the grades (mean ± SD) of G1 (85.1 ± 6.6%) and G2 (86.2 ± 9.1%) with the grades of a baseline test that was previously obtained when students submitted to the study (P = 0.725). Regarding the tooth carving assessment, the dental carving quality by students of G1 has significantly improved, except for tooth #23 (P = 0.096). Theoretical reinforcement of dental anatomy seems to improve the students' carving performance but does not enhance their knowledge about dental anatomy. Anat Sci Educ 11: 377-384. © 2017 American Association of Anatomists.

Cellulose Nanocrystal Membranes as Excipients for Drug Delivery Systems.

In this work, cellulose nanocrystals (CNCs) were obtained from flax fibers by an acid hydrolysis assisted by sonochemistry in order to reduce reaction times. The cavitation inducted during hydrolysis resulted in CNC with uniform shapes, and thus further pretreatments into the cellulose are not required. The obtained CNC exhibited a homogeneous morphology and high crystallinity, as well as typical values for surface charge. Additionally, CNC membranes were developed from CNC solution to evaluation as a drug delivery system by the incorporation of a model drug. The drug delivery studies were carried out using chlorhexidine (CHX) as a drug and the antimicrobial efficiency of the CNC membrane loaded with CHX was examined against Gram-positive bacteria Staphylococcus aureus (S. Aureus). The release of CHX from the CNC membranes is determined by UV-Vis. The obtaining methodology of the membranes proved to be simple, and these early studies showed a potential use in antibiotic drug delivery systems due to the release kinetics and the satisfactory antimicrobial activity.

Aliphatic fatty acids and esters: inhibition of growth and exoenzyme production of Candida, and their cytotoxicity in vitro: anti-Candida effect and cytotoxicity of fatty acids and esters.

The secretion of extracellular phospholipases and proteinases of Candida has been described as a relevant virulence factor in human infections. Aliphatic fatty acids have antimicrobial properties, but the mechanism by which they affect the virulence factors of microorganisms, such as Candida, is still unclear, and there are a few reports about their toxicity. The current study investigated the in vitro antifungal activity, exoenzyme production and cytotoxicity of some aliphatic fatty acids and their ester derivatives against the Candida species. The minimum inhibitory concentration and minimum fungicidal concentrations of aliphatic medium-chain fatty acids, methyl and ethyl esters were performed using the CLSI M27-A3 method and the cytotoxicity assay was performed according to ISO 10993-5. The influence of these compounds in the inhibition of the production of hydrolytic enzymes, phospholipases and proteinases by Candida was also investigated. Data analysis was performed using the one-way ANOVA method (p≤0.05). In relation to the MIC against Candida species, the fatty acid with the best result was Lauric acid, although its ester derivatives showed no activity. The inhibition of phospholipase production was more significant than the inhibition of proteinase production by Candida. Tested fatty acids revealed more than 80% cell viability in their MIC concentrations. Additionally, a cell viability of 100% was reported at concentrations of anti-enzymatic effect. Therefore, the potential use of these fatty acids could be the basis for more antimicrobial tests.

7-chloroquinolin-4-yl arylhydrazone derivatives: synthesis and antifungal activity.

Fifteen 7-chloro-4-arylhydrazonequinolines have been evaluated for their in vitro antifungal activity against eight oral fungi: Candida albicans, C. parapsilosis, C. lipolytica, C. tropicalis, C. famata, C. glabrata, Rhodutorula mucilaginosa, and R. glutinis. Several compounds exhibited minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) activities comparable with the first-line drug fluconazole. These results could be considered as an important starting point for the rational design of new antifungal agents.

Teor de flúor e propriedades erosivas dos sucos de frutas naturais concentrados / Fluoride levels and erosive properties of natural concentrated fruit juices

A preocupação com uma dieta saudável tem ocasionado aumento no consumo de frutas e sucos naturais. Orientações quanto à ingestão de sucos ácidos são extremamente importantes na prevenção e tratamento de lesões de erosão dental. O objetivo do presente trabalho foi determinar o pH e a concentração de fluoretos em sucos concentrados e diferentes frutas comercializadas na cidade de Pelotas-RS. Foram selecionadas amostras de sete frutas: maçã, laranja, maracujá, uva, melão, limão e abacaxi. As amostras foram processadas em triplicata. As frutas foram trituradas em mixer Walita (modelo HL 3235) para obtenção dos sucos e, em seguida, os mesmos foram centrifugados em centrífuga Sigma (modelo 4K15), a 19ºC e a 5100rpm por 10 minutos. As análises dos sucos concentrados foram feitas no Laboratório de Determinação de Fluoretos do Departamento de Bioquímica da UFPel. A mensuração do pH e a determinação do teor de flúor foram realizadas com aparelho potenciométrico microprocessado (ANALION - AN 2000). Os resultados mostraram que o pH dos diferentes sucos foi de: 2,25 (limão); 2,69 (maracujá); 3,30 (abacaxi); 3,32 (laranja); 3,88 (maçã); 4,14 (uva) e 6,04 (melão). O teor de flúor iônico livre nas frutas não ultrapassou 0,04ppm. Com base na metodologia empregada, concluiu-se que a maioria dos sucos de frutas testados apresentou potencial de desmineralização dos tecidos dentários e o teor de flúor presente em tais sucos foi inexpressivo