Effect of thermocycling on the tensile and shear bond strengths of three soft liners to a denture base resin

STATEMENT OF PROBLEM: In clinical practice, loss of adhesion between the silicone-based denture liner and the denture base resin is always an undesirable event that might cause loss of material softness, water sorption, bacterial colonization and functional failure of the prosthesis. PURPOSE: This study evaluated the effect of thermocycling on tensile and shear bond strengths of three soft liner materials to a denture base acrylic resin. MATERIAL AND METHODS: Three resilient liners (Mucopren-Soft, Mollosil-Plus and Dentusil) and a heat-polymerized acrylic resin (QC-20) were processed according to manufacturers' directions. Sixty specimens (14 x 14 mm cross-sectional area) per bond strength test (20 for each liner) were fabricated and either stored in water at 37ºC for 24 hours (control groups; n=10) or thermocycled 3,000 times in water between 5ºC and 55ºC (test groups; n=10). The specimens were tested in tensile and shear strength in a universal testing machine until fracture. Bond strength means were compared between water-stored and thermocycled groups for each material, as well as among materials for each treatment (water storage or thermocycling). Failure mode (adhesive, cohesive and mixed) after debonding was assessed. Data were analyzed statistically by paired Student's t-test and ANOVA at 5% significance level. RESULTS: The water-stored groups had statistically significant higher bond strengths than the thermocycled groups (

Ultrafine grained titanium for biomedical applications: An overview of performance

AbstractUltrafine grain sized titanium (UFG Ti) obtained by severe plastic deformation presents a bright potential for biomedical applications because it provides the strength of titanium alloys without toxic alloying elements, such as Al and V that, by dissolving away from the implant, may be harmful to human health. The most recent developments and challenges in this field are reviewed. UFG Ti mini-devices were implanted in rabbits and the removal torque was compared with that of conventional commercially pure (cp) grain sized Ti Grade 2 and Ti6Al4V alloy Grade 5. The osseointegration of the UFG Ti was slightly superior of that of cp Ti Grade 2. The microstructure and mechanical properties of the UFG Ti, with special emphasis on dental implant application are reviewed and some additional properties evaluated and presented

GROWTH AND MINERAL NUTRITION IN SEEDLINGS OF JACARANDÁ-DA-BAHIA SUBJECTED TO NUTRIENT DEPRIVATION

AbstractWith the objective of evaluating the nutritional requirements and the effects of nutrient deprivation in developing of Jacarandá da Bahia seedlings (Dalbergia nigra (Vellozo) Freire Allemao ex Bentham), a greenhouse experiment was conducted. The experiment had fully randomized design, with 12 treatments and 8 replications. The following treatments were applied: Complete 1 (C1-fertilized with N, P, K, S, B, Cu, Zn and liming as Ca and Mg sources), complete 2 (Complete 1 – liming with CaSO4.2H2O and MgSO4.7H2O as Ca and Mg sources), C1-N, C1-P, C1-K, C1-S, C1-B, C1-Zn, C1-liming, C2-Ca, C2-Mg and control. Diameter and height were measured and plants were separated into aerial part and root system. Samples were dried, weighed and levels of nutrients in the aerial dry matter were measured. Phosphorus was the most growth limiting factor, the sequence of nutritional requirements presented by Jacarandá da Bahia seedlings in relation to the complete treatment was: P > Ca > B > K > S > Zn > Mg > N.Keywords: Missing element; Dalbergia nigra; rainforest; hardwood. ResumoCrescimento e nutrição mineral de mudas de jacarandá-da-bahia sob efeito da omissão de nutrientes. Com o objetivo de avaliar exigências nutricionais e os efeitos da omissão de nutrientes no desenvolvimento de mudas de Jacarandá da Bahia (Dalbergia nigra (Vellozo) Freire Allemao ex Bentham), conduziu-se um experimento com o uso da técnica de elemento faltante. Foram empregados 12 tratamentos, em um delineamento inteiramente casualizado com oito repetições. Adotaram-se os seguintes tratamentos: Completo 1 (adubado com N, P, K, S, B, Cu, Zn e calagem como fonte de Ca e Mg e corrigindo acidez do solo), completo 2 (completo 1 – calagem tendo CaSO4.2H2O e MgSO4.7H2O como fontes de Ca e Mg sem corrigir acidez do solo), C1-N, C1-P, C1-K, C1-S, C1-B, C1-Zn, C1-calagem, C2-Ca, C2-Mg e testemunha. Foram medidos diâmetro e altura das plantas e separadas em parte aérea e sistema radicular. As mudas foram secas, pesadas e foram determinados os teores de nutrientes na matéria seca da parte aérea. O fósforo foi o nutriente mais limitante ao crescimento de jacarandá da Bahia; a sequência de exigência nutricional apresentada pelas mudas de Jacarandá da Bahia em relação ao tratamento completo em ordem decrescente foi: P > Ca > B > K > S > Zn > Mg > N.Palavras-chave: Elemento faltante; Dalbergia nigra; Mata Atlântica; Madeira nobre.AbstractWith the objective of evaluating the nutritional requirements and the effects of nutrient deprivation in developing of Jacarandá da Bahia seedlings (Dalbergia nigra (Vellozo) Freire Allemao ex Bentham), a greenhouse experiment was conducted. The experiment had fully randomized design, with 12 treatments and 8 replications. The following treatments were applied: Complete 1 (C1-fertilized with N, P, K, S, B, Cu, Zn and liming as Ca and Mg sources), complete 2 (Complete 1 – liming with CaSO4.2H2O and MgSO4.7H2O as Ca and Mg sources), C1-N, C1-P, C1-K, C1-S, C1-B, C1-Zn, C1-liming, C2-Ca, C2-Mg and control. Diameter and height were measured and plants were separated into aerial part and root system. Samples were dried, weighed and levels of nutrients in the aerial dry matter were measured. Phosphorus was the most growth limiting factor, the sequence of nutritional requirements presented by Jacarandá da Bahia seedlings in relation to the complete treatment was: P > Ca > B > K > S > Zn > Mg > N.Keywords: Missing element; Dalbergia nigra; rainforest; hardwood

Frictional resistance of self-ligating versus conventional brackets in different bracket-archwire-angle combinations

Objective: To compare the influence of archwire material (NiTi, beta-Ti and stainless steel) and brackets design (self-ligating and conventional) on the frictional force resistance. Material and Methods: Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M). The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement. Results: Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials. Conclusion: even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material

Effect of focal adhesion kinase inhibition on osteoblastic cells grown on titanium with different topographies

Objective:The present study aimed to investigate the participation of focal adhesion kinases (FAK) in interactions between osteoblastic cells and titanium (Ti) surfaces with three different topographies, namely, untreated (US), microstructured (MS), and nanostructured (NS). Methodology; Osteoblasts harvested from the calvarial bones of 3-day-old rats were cultured on US, MS and NS discs in the presence of PF-573228 (FAK inhibitor) to evaluate osteoblastic differentiation. After 24 h, we evaluated osteoblast morphology and vinculin expression, and on day 10, the following parameters: gene expression of osteoblastic markers and integrin signaling components, FAK protein expression and alkaline phosphatase (ALP) activity. A smooth surface, porosities at the microscale level, and nanocavities were observed in US, MS, and NS, respectively. Results: FAK inhibition decreased the number of filopodia in cells grown on US and MS compared with that in NS. FAK inhibition decreased the gene expression of Alp, bone sialoprotein, osteocalcin, and ALP activity in cells grown on all evaluated surfaces. FAK inhibition did not affect the gene expression of Fak, integrin alpha 1 ( Itga1 ) and integrin beta 1 ( Itgb1 ) in cells grown on MS, increased the gene expression of Fak in cells grown on NS, and increased the gene expression of Itga1 and Itgb1 in cells grown on US and NS. Moreover, FAK protein expression decreased in cells cultured on US but increased in cells cultured on MS and NS after FAK inhibition; no difference in the expression of vinculin was observed among cells grown on all surfaces. Conclusions: Our data demonstrate the relevance of FAK in the interactions between osteoblastic cells and Ti surfaces regardless of surface topography. Nanotopography positively regulated FAK expression and integrin signaling pathway components during osteoblast differentiation. In this context, the development of Ti surfaces with the ability to upregulate FAK activity could positively impact the process of implant osseointegration

Relação entre os parâmetros de rugosidade 3D e a molhabilidade do titânio com grãos micrométricos e sub-micrométricos

O titânio comercialmente puro (Ti cp) é o principal material usado na fabricação dos implantes dentários osseointegráveis. Para melhorar os índices de sucesso do tratamento odontológico e reduzir o tempo de osseointegração dos implantes, foram desenvolvidas várias metodologias de tratamento da superfície dos implantes. Para caracterizar as morfologias das superfícies dos implantes são usadas as análises no microscópio eletrônico de varredura (MEV), rugosidade, molhabilidade, identificação de possíveis contaminantes, ensaios in-vitro de culturas de células e in-vivo com animais. Entre as técnicas citadas, as mais usadas são as análises no MEV, as medidas dos parâmetros da rugosidade e da molhabilidade. Alguns trabalhos disponíveis na literatura sugerem a caracterização somente do valor de Ra sem apresentar uma explicação para a escolha deste parâmetro. No presente trabalho é feita a proposta de um modelo matemático para quantificar a relação entre os vários parâmetros da rugosidade 3D (Ra, Rq, Rz, Rms, Pico, Vale, PV, R3z e Smax) com a molhabilidade e a energia de superfície do Ti cp com dois tamanhos de grão (micrométricos e sub-micrométricos) e submetidos ao tratamento com ácido. Os resultados mostraram que para o nível de confiança de 95%, as propriedades das superfícies do Ti cp tratados com ácido são mais influenciadas pelos parâmetros de rugosidade Ra e Rms. Palavras-chave: titânio, rugosidade, molhabilidade, metodologia de LASS

Assessment of the total organic carbon and conductivity in consecutive dyeings with reactive dyestuffs using treated effluent by UV/H2O2 photocatalysis

The paper was monitored the conductivity (g·L-1 of NaCl), the absorbances values (Abs) and the amount of TOC (total organic carbon), before and after five consecutive dyeings made with reuse water, obtained from treated effluent by UV/H2O2 photocatalysis. All rates of decolorization were above 92%, the removal of total organic carbon was above 89% in all treatments and the economy of NaCl was from 3.10 in the first recipe, 3.17 in the second, 3.49 in the third, 3.79 in the fourth and 4.05 in the fifth recipe. The five dyeings compared with same dyeings made with deionized water presented a color deviation (ΔE*) below 1. The conventional dyeings would consume 80 L/kg against 40 L/kg used in the dyeing process proposed in this study, representing a great economy of water, with no discharge of effluents142139144sem informaçãosem informaçã