Osteogenic differentiation of rat bone mesenchymal stem cells cultured on poly (hydroxybutyrate-co-hydroxyvalerate), poly (ε-caprolactone) scaffolds.

Bioresorbable biomaterials can fill bone defects and act as temporary scaffold to recruit MSCs to stimulate their differentiation. Among the different bioresorbable polymers studied, this work focuses on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL). Were prepared blends of PHBV and PCL to obtain PHBV based biomaterials with good tenacity, important for bone tissue repair, associated with biocompatible properties of PCL. This study assesses the viability of Vero cells on scaffolds of PHBV, PCL, and their blends and the osteogenic differentiation of mesenchymal stem cells (MSCs). Materials were characterized in surface morphology, DSC and Impact Strength (IS). Vero cells and MSCs were assessed by MTT assay, cytochemical and SEM analysis. MSC osteogenic differentiation was evaluated through alizarin red staining and ALP activity. We found some roughness onto surface materials. DSC showed that the blends presented two distinct melting peaks, characteristic of immiscible blends. IS test confirmed that PHBV-PCL blends is an alternative for increase the tenacity of PHBV. MTT assay showed cells with high metabolic activities on extract toxicity test, but with low activity in the direct contact test. SEM analysis showed spreading cells with irregular and flattened morphology on different substrates. Cytochemical study revealed that MSCs maintained their morphology, although in smaller number for MSCs. The development of nodules of mineralized organic matrix in MSC cultures was identified by alizarin red staining and osteogenic differentiation was confirmed by the quantification of ALP activity. Thus, our scaffolds did not interfere on viability of Vero cells or the osteogenic differentiation of MSCs.

Assessment of the usage of biodegradable polymeric matrix in vaginal devices to sustain progesterone release in cows.

The usage of timed artificial insemination (TAI) at a low cost leading to better reproductive rates has been the aim of several research groups in the field. Usually during TAI protocols, sustained progesterone (P4 ) release devices are employed. Most devices are constituted of a nylon skeleton covered with a silicon layer with P4 . A device based on biopolymers was developed in order to reduce costs and decrease its environmental impact. In this study, we compared the kinetics of sustained progesterone release among devices manufactured with a polymeric blend made of polyhydroxybutyrate-valerate (PHBV) and poly-ε-caprolactone (PCL) (DISP) which were compared with DIB® (Internal Bovine Device) used as the control. In the in vitro and in vivo progesterone release tests, two types of biopolymer-based devices with a superficial area of 147 cm2 were used: DISP8 (46% PHBV, 46% PCL and 8% P4 ; n = 4), DISP10 (45% PHBV, 45% PCL, 10% P4 ; n = 4) and DIB® (1 g P4 , 120 cm2 area; n = 3). The in vitro tests were carried out according to USP XXIII specifications and were performed in a dissolutor sink using an alcohol/water mixture (60/40 v/v) as a release media and samples were collected at 2 min, 2, 4, 8, 12, 24, 48, 60, 72, 84 and 96 h. P4 concentrations were measured through spectrophotometry in a 244 nm long wave. Three to 3 comparisons of angular coefficients of the straight lines obtained by regression analysis of accumulated P4 concentrations as a function of square root of time were carried out. Furthermore, the diffusion coefficient values of P4 were also determined for DISP8 and DISP10. The results showed that the concentrations of P4 were higher in the DISP10 (774.63 ± 45.26 µg/cm2 /t1/2 ) compared to DISP8 (566.17 ± 3.68 µg/cm2 /t1/2 ) (P < 0.05). However, both DISP10 and DISP8 P4 concentrations did not differ from DIB® (677.39 ± 16.13 µg/cm2 /t1/2 ). For the analysis of released quantities per day of the in vitro test, four periods were considered: 0-24, 24-48, 48-72 and 72-96 h. In the first 24 h, DISP8 released significantly less P4 than DISP10 or DIB®, which did not differ among them. Between 24 and 48 h, DISP10 released significantly more P4 than DIB®. DISP8 released an intermediate P4 amount and did not differ significantly from DIB® or DISP10. Between 48 and 72 h, P4 quantity released by DISP10 was significant higher (P < 0.01) than that of DIB® and DISP8, which did not differ among themselves. Between 72 and 96 h, DISP10 released significantly more P4 than DIB®, and DISP8 released an intermediate amount which did not differ from DIB® or DISP10 (P < 0.01). There was interaction between treatment and time (P = 0.0024). The diffusion coefficient values were: 1.36 × 10-8 (cm2 /s) for DISP10 and 1.12 × 10-8 (cm2 /s) for DISP8. For the in vivo test, ovariectomized crossbred cows received DIB® (n = 4) or DISP8 (n = 8) in an alternate design with a non-balanced sequence (cross-over) added of measures repeated in time referring to 16 days of blood samples collection. Samples were analyzed through radioimmunoassay in solid phase using the commercial kit of DPC (Diagnostics Products Corporation). Plasma concentrations of P4 peaked at 4 h after the placement of the device, this being the only time in which plasma P4 concentrations differed between DIB® (11.45 ± 1.96) compared with DISP8 (9.23 ± 1.15 ng/mL) (P = 0.027). On day 8, plasma P4 concentrations were similar for DIB® (2.44 ± 0.09) and DISP8 (1.89 ± 0.13 ng/mL) (P = 0.58) showing that both devices were able to keep P4 concentrations above 1 ng/mL in the plasma of the cow during the 16 day in vivo test. In conclusion, devices manufactured with the blend of PHBV/PCL biopolymers can sustain the release of P4 in a similar manner as silicon.

In vitro study of the antibacterial properties and impact strength of dental acrylic resins modified with a nanomaterial.

STATEMENT OF PROBLEM: The accumulation of bacteria on the surface of dental prostheses can lead to systemic disease. PURPOSE: The purpose of this in vitro study was to evaluate the growth of Staphylococcus aureus and Pseudomonas aeruginosa on the surface of autopolymerizing (AP) and heat-polymerizing (HP) acrylic resins incorporated with nanostructured silver vanadate (ß-AgVO3) and its impact strength. MATERIAL AND METHODS: For each resin, 216 circular specimens (9 × 2 mm) were prepared for microbiologic analysis and 60 rectangular specimens (65 × 10 × 3.3 mm) for mechanical analysis, according to the percentage of ß-AgVO3: 0%, control group; 0.5%; 1%; 2.5%; 5%; and 10%. After a biofilm had formed, the metabolic activity of the bacteria was measured using the XTT reduction assay (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) (n=8), and the number of viable cells was determined by counting colony forming units per milliliter (CFU/mL) (n=8). Confocal laser scanning microscopy (CLSM) was used to complement the analyses (n=2). The mechanical behavior was evaluated by impact strength assays (n=10). Data were analyzed by 2-way ANOVA, followed by the Tukey honestly significant difference (HSD) post hoc test (α=.05). RESULTS: The addition of 5% and 10% ß-AgVO3 significantly decreased the metabolic activity of P. aeruginosa for both resins (P<.05). The HP resin promoted a greater reduction in metabolic activity than the AP resin (P<.05). No difference was found in the metabolic activity of S. aureus according to the XTT (P>.05). The number of CFU/mL for S. aureus and P. aeruginosa decreased significantly when 5% and 10% ß-AgVO3 were added (P<.001). These concentrations significantly reduced the impact strength of the resins (P<.001) because the system was weakened by the presence of clusters of ß-AgVO3. CONCLUSION: The addition of ß-AgVO3 can provide acrylic resins with antibacterial activity but reduces their impact strength. More efficient addition methods should be investigated.

Avaliação do comportamento mecânico de modelos odontológicos obtidos em resina de poliuretano / Evaluation of the mechanical behavior of odontological models in polyurethane resin

Este estudo avaliou o comportamento mecânico de uma resina de poliuretano Quartz-die (Zermack - Itália) empregada na modelagem odontológica comparando-a com o gesso tipo IV Durone (Dentsply - Brasil). Uma matriz metálica moldada com silicona de condensação Speedex (Coltène - Suiça) proporcionou corpos de prova com 12mm de altura por 6mm de diâmetro. Oito corpos de prova em resina de poliuretano e oito em gesso tipo IV (Durone) foram submetidos a ensaio de compressão na máquina de ensaios universal EMIC DL 2000, com célula de carga de 2000Kgf e velocidade de 0,05mm/min. Oito corpos de prova em resina de poliuretano e oito em gesso tipo IV obtidos a partir de uma matriz metálica hexagonal foram ensaiados noDurômetro Sussen Wolpert tipo Testor HTl, empregando penetrador esférico de 12,7mm, estabelecendo valores para dureza Rockwell. Os valores obtidos foram submetidos ao teste não-paramétrico de Kruskall-Walliscom p<0,05. Dentro dos parâmetros adotados neste estudo pôde-se concluir que a resina de poliuretano Quartz-die apresentou menor resistência à compressão e menor dureza superficial que o gesso tipo IV Durone.

Análise da capacidade de reprodução de detalhes expressa por diferentes materiais de modelagem / Analysis of the capacity to reproduce details expressed by different modeling materials

Este estudo objetivou avaliar a capacidade de reprodução de detalhes presentes no molde por materiais de modelagem à base de gipsita Gesso pedra tipo IV, Durone, (Dentsply); Gesso pedra tipo IV, Fuji Rock EP,(GC); Gesso pedra tipo IV, Resinado Rock Plus, (Polidental); Gesso pedra tipo V, Durone, (Dentsply) epolímeros: resinas epóxicas Epoxiglass 1504, (Epoxiglass), resina epóxica Epoxiglass 1504 modificada com diatomita pura e silanizada. A resina e seu endurecedor foram carregados com diatomita numa relação de30%. A diatomita foi tratada com Silano Silquest A 187, (Crompton S/A). A resina modificada foi manipuladaem uma relação de 35%. Empregando-se silicona de adição Presidente (Kit de silicona leve e pesada, Coltène) realizaram-se três moldagens de uma matriz metálica com quatro hastes contendo sulcos dimensionados. Os corpos de prova foram analisados em microscópio óptico com aumento de 40 vezes (Measurescope Nikon, procedência Nippon Kogaru K. K.). Os resultados expressos por gessos e resinas foram analisados com o teste Variância e Tukey (p<0,05). Verificou-se que não há diferenças estatisticamente significantes entre os gessos e resinas analisadas. Concluiu-se que o carregamento da resina epóxica com diatomita ou com diatomita silanizada não reduz a sua capacidade em reproduzir detalhes presentes no molde. Com a metodologia empregada, não houve diferença entre gessos tipo IV e V e resina epóxica pura ou modificada com diatomita na capacidadede reprodução de detalhes presentes no molde.

Impact fracture strength applied to dental modeling materials

The aim of the present study was to analyze the impact fracture strength using plaster and resin modeling materials. The analysis was made using nine dies having plaster III bases and internal portion of laboratory-type addition silicone. Nine test specimens were produced of each following material: typeIV Durone plaster, type IV Fuji Rock plaster, type IV Rock Plus plaster, type V Durone plaster, Epoxiglass 1504 epoxy resin, epoxy resin modified with diatomite and epoxy resin modified with diatomite. The tests were performed in a Ceast testing machine. At the moment of fracture, the machine recorded avalue (Energy), using a formula to obtain the impact strength value in joules per meter. Statistical and variance analyses and Student's t test revealed that pure or silanized diatomite increased the impact fracture strength of models made of Epoxiglass 1504 epoxy resin and that silanizing the filler led toa further gain in impact fracture strength. The models made of Epoxiglass 1504 displayed greater impact fracture strength than those made of plaster types IV and V. No statistically significant differences were found among the analyzed plasters. Models prepared with epoxy resin displayed in general greater impact fracture strength than models made of plasters.

Comportamento dimensional de resina epóxica industrial carregada com diatomita para ser empregada na modelagem odontológica / Dimensional behavior of industrial epoxy resin loaded with diatomite used for dental modeling

A proposta desse estudo foi avaliar o comportamento dimensional de uma resina epóxica industrial carregada com diatomita para ser empregada na modelagem odontológica. Modificou-se a resina epóxica Epoxiglass 1504 e o seu endurecedor (Epoxiglass Ind. e Com. de Produtos Químicos Ltda., Diadema-Brasil) com adição de 30 por cento em peso de diatomita pura e silanizada com Silano Siquest A187 (Crompton S/A, Itatiba-Brasil). Empregou-se matriz com marcações no sentido vertical distantes em 4.000µm e no sentido horizontal em 1.328µm. Os modelos produzidos em resina epóxica pura, modificada com diatomita, modificada com diatomita silanizada foram analisados em microscópio Nikon (Japão). Os resultados foram comparados a obtidos com modelos em Gesso tipo IV Duone micro granulado, (Dentsply-USA); Gesso tipo IV, Fuji Rock EP, (GC América Inc-USA); Gesso tipo IV Resinado, Rock Plus, (Polidental-Brasil); Gesso pedra tipo V...