Rubbing time and bonding performance of one-step adhesives to primary enamel and dentin

Abstract Objectives: This study investigated whether increasing the concentration of acidic monomers in one-step adhesives would allow reducing their application time without interfering with the bonding ability to primary enamel and dentin. Material and methods: Experimental one-step self-etch adhesives were formulated with 5 wt% (AD5), 20 wt% (AD20), or 35 wt% (AD35) acidic monomer. The adhesives were applied using rubbing motion for 5, 10, or 20 s. Bond strengths to primary enamel and dentin were tested under shear stress. A commercial etch-and-rinse adhesive (Single Bond 2; 3M ESPE) served as reference. Scanning electron microscopy was used to observe the morphology of bonded interfaces. Data were analysed at p<0.05. Results: In enamel, AD35 had higher bond strength when rubbed for at least 10 s, while application for 5 s generated lower bond strength. In dentin, increased acidic monomer improved bonding only for 20 s rubbing time. The etch-and-rinse adhesive yielded higher bond strength to enamel and similar bonding to dentin as compared with the self-etch adhesives. The adhesive layer was thicker and more irregular for the etch-and-rinse material, with no appreciable differences among the self-etch systems. Conclusion: Overall, increasing the acidic monomer concentration only led to an increase in bond strength to enamel when the rubbing time was at least 10 s. In dentin, despite the increase in bond strength with longer rubbing times, the results favoured the experimental adhesives compared to the conventional adhesive. Reduced rubbing time of self-etch adhesives should be avoided in the clinical setup.

Utilization of a waste glycerol fraction using and reusing immobilized Gluconobacter oxydans ATCC 621 cell extract

Background: Depletion of petroleum resources has enforced the search for alternative sources of renewable energy. Introduction of biofuels into the market was expected to become a solution to this disadvantageous situation. Attempts to cover fuel demand have, however, caused another severe problem­the waste glycerol generated during biodiesel production at a concentration of approximately 10% w/w. This, in turn, prompted a global search for effective methods of valorization of the waste fraction of glycerol. Results: Utilization of the waste fraction at 48 h with an initial glycerol concentration of 30 g·L-1 and proceeding with 62% efficiency enabled the production of 9 g·L-1 dihydroxyacetone at 50% substrate consumption. The re-use of the immobilized biocatalyst resulted in a similar concentration of dihydroxyacetone (8.7 g·L-1) in two-fold shorter time, with an efficiency of 85% and lower substrate consumption (35%). Conclusions: The method proposed in this work is based on the conversion of waste glycerol to dihydroxyacetone in a reaction catalyzed by immobilized Gluconobacter oxydans cell extract with glycerol dehydrogenase activity, and it could be an effective way to convert waste glycerol into a valuable product.

Glycerol Salicylate-based Pulp-Capping Material Containing Portland Cement

The purpose of this study was to evaluate the water sorption, solubility, pH and ability to diffuse into dentin of a glycerol salicylate-based, pulp-capping cement in comparison to a conventional calcium hydroxide-based pulp capping material (Hydcal). An experimental cement was developed containing 60% glycerol salicylate resin, 10% methyl salicylate, 25% calcium hydroxide and 5% Portland cement. Water sorption and solubility were determined based on mass changes in the samples before and after the immersion in distilled water for 7 days. Material discs were stored in distilled water for 24 h, 7 days and 28 days, and a digital pHmeter was used to measure the pH of water. The cement's ability to diffuse into bovine dentin was assessed by Raman spectroscopy. The glycerol salicylate-based cement presented higher water sorption and lower solubility than Hydcal. The pH of water used to store the samples increased for both cements, reaching 12.59±0.06 and 12.54±0.05 after 7 days, for Hydcal and glycerol salicylate-based cements, respectively. Both cements were able to turn alkaline the medium at 24 h and sustain its alkalinity after 28 days. Hydcal exhibited an intense diffusion into dentin up to 40 µm deep, and the glycerol salicylate-based cement penetrated 20 µm. The experimental glycerol salicylate-based cement presents good sorption, solubility, ability to alkalize the surrounding tissues and diffusion into dentin to be used as pulp capping material.

O objetivo deste estudo foi avaliar a sorção e solubilidade em água, pH e habilidade de difusão na dentina de um cimento para capeamento pulpar à base de glicerol salicilato e compará-lo a um cimento comercial para capeamento pulpar à base de hidróxido de cálcio (Hydcal). Um cimento experimental contendo 60% de resina de glicerol salicilato, 10% de salicilato de metila, 25% de hidróxido de cálcio e 5% de cimento Portland foi formulado. Sorção e solubilidade em água foram determinadas a partir da alteração na massa de espécimes antes e após a imersão em água destilada por 7 dias. Discos dos cimentos foram armazenados em água destilada por 24h, 7 dias e 28 dias e o pH da água foi aferido após cada período. A habilidade de difundir-se no interior de dentina bovina foi avaliada por espectroscopia Raman. O cimento à base de glicerol salicilato apresentou maior sorção e menor solubilidade em comparação com o Hydcal. O pH da água de armazenamento dos espécimes aumentou para ambos os cimentos, chegando a 12,59±0,06 e 12,54±0,05 após 7 dias, para o Hydcal e o cimento à base de glicerol salicilato, respectivamente. Os cimentos foram capazes de promover a alcalinização do meio após 24h e sustentaram a alcalinidade após 28 dias. Hydcal exibiu intensa difusão na dentina até 40 μm de profundidade e o cimento à base de glicerol salicilato penetrou 20 μm. O cimento experimental à base de glicerol salicilato apresentou adequada sorção, solubilidade, habilidade de alcalinizar o meio e difundir-se no interior da dentina para uso como um material para capeamento pulpar.

Glicerina bruta no suplemento e seus efeitos nas características da carcaça e nos componentes do peso vivo de cordeiros lactentes / Crude glycerin in supplement and its effects on carcass characteristics and live weight components in suckling lambs

Objetivou-se avaliar o efeito da porcentagem de glicerina bruta em suplementos sobre as características da carcaça e os componentes do peso vivo de cordeiros lactentes mantidos em pasto de azevém. Foram utilizados 32 cordeiros lactentes, distribuídos nos tratamentos: 0, 10, 20 e 30% de glicerina bruta na matéria seca, em substituição ao milho, no suplemento isoproteico (18% de PB na matéria seca) fornecido diariamente em quantidade equivalente a 2% do peso corporal. As porcentagens de glicerina bruta tiveram efeito linear decrescente sobre peso de carcaça quente, peso de carcaça fria, rendimento de carcaça quente e rendimento de carcaça fria, enquanto as perdas pelo jejum aumentaram. O peso da paleta e o peso do costilhar diminuíram, enquanto a proporção de perna aumentou com o incremento de glicerina bruta no suplemento. Na composição tecidual da paleta, observou-se que a gordura subcutânea, a gordura intermuscular e a gordura total da paleta decresceram linearmente segundo as porcentagens de glicerina bruta. Sobre os componentes do peso vivo, observaram-se diferenças nas proporções de pele, rúmen, omaso, intestino grosso, que aumentaram, enquanto a de gordura renal diminuiu linearmente. Conclui-se que o uso de glicerina bruta em até 30% em suplemento fornecido em comedouro privativo para cordeiros lactentes mantidos em pasto de azevém interfere nas características da carcaça e nos componentes corporais.

The objective was to evaluate the effect of crude glycerin levels in supplement on carcass characteristics and live weight components of suckling lambs maintained on ryegrass pasture. Thirty two suckling lambs were used and were distributed among the treatments: 0, 10, 20 and 30% crude glycerin, in replacement of corn, in the isoproteic supplement (18% CP) provided daily in amounts equivalent to 2% of body weight. The levels of crude glycerin had negative linear effects on hot and cold carcass weight, hot and cold carcass yield but an increasing effect was observed on gastrointestinal content and fasting losses. The shoulder and rib weights decreased, while the leg proportion increased with the elevation of crude glycerin use. In the tissue composition of the shoulder, it was observed that the subcutaneous fat, intermuscular fat and total fat decreased linearly according to the levels of crude glycerin. Regarding body weight components, differences were observed in the proportions of skin, rumen, omasum, large intestine, which increased, while the kidney fat decreases linearly. The use of crude glycerin in up to 30% in the supplement provided in creep feeding for suckling lambs kept in ryegrass pasture influences carcass characteristics and corporal components.

Avaliação morfológica e por imagem radiográfica da matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina para reparação de falhas ósseas em tíbias de coelhos / Morphological evaluation and radiographic image of fragmented heterolog mineralized bone matrix and methylmethacrylate preserved in glycerin to repair osseous defects in tibias of rabbits

Os traumas que resultam em fraturas ósseas, principalmente as cominutivas, têm uma importância muito grande na rotina clínico-cirúrgica veterinária e humana. Foi realizada falha segmentar de 6mm na região metafisária medial da tíbia esquerda de 12 coelhos, a qual foi preenchida com implante constituído de matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina (98%) para a sua reconstrução. Foi realizada avaliação morfológica e radiológica aos 30, 60, 90 e 120 dias e observou-se a incorporação do implante ao leito receptor, em 100% dos casos, mostrando ser biologicamente compatível, pois promoveu a reparação das falhas ósseas, sem sinais de infecção, migração e/ou rejeição, sendo uma opção de substituto para preencher defeitos ósseos.

The traumas that result in bone fractures, especially comminuted, have high importance in veterinary and human surgical routine. A 6mm of segmental defect was performed at the medial metaphyseal region of the left tibia of 12 rabbits and an association of fragmented heterologue mineralized bone matrix and methylmethacrylate conserved in glycerin (98%) was used as a graft to fill the bone defect. To evaluate the procedure morphological and radiological exams were performed after 30, 60, 90 and 120 days. There was gradual integration of the bone graft in the receptor bed in 100% of the cases showing that the material is biologically compatible as it promotes bone defect reparation without signs of infection, migration and/or rejection and can be considered one more option to be used as a substitute to fill bone defects.

Influence of serum and necrotic soft tissue on the antimicrobial effects of intracanal medicaments

The purpose of this study was to investigate the influence of serum and necrotic soft tissue on the antimicrobial activity of intracanal medicaments. The medicaments tested were: calcium hydroxyde/glycerin paste, calcium hydroxide/chlorhexidine paste, calcium hydroxide/camphorated paramonochlorophenol/glycerin paste, and chlorhexidine/zinc oxide paste. Survival of Enterococcus faecalis and Candida albicans exposed to the medicaments tested in the presence or absence of serum or necrotic tissue was monitored in three in vitro experiments where samples for culturing were taken at different time periods. The overall results demonstrated that the antimicrobial activity of all intracanal medicaments tested was slowed down in the presence of necrotic tissue. Calcium hydroxide pastes in glycerin or chlorhexidine were significantly affected by serum. Of the medicaments tested in this study, the least affected was the calcium hydroxide/camphorated paramonochlorophenol/glycerin paste.

O objetivo deste estudo foi avaliar a influência do soro e de tecido mole necrosado na atividade antimicrobiana de medicamentos intra-canais. Os medicamentos testados foram pastas de hidróxido de cálcio/glicerina, hidróxido de cálcio/clorexidina, hidróxido de cálcio/paramonoclorofenol canforado/glicerina e clorexidina/óxido de zinco. A sobrevivência de Enterococcus faecalis e Candida albicans expostos aos medicamentos na presença ou ausência de soro ou tecido necrosado foi monitorada em três experimentos in vitro nos quais amostras para cultura foram avaliadas em diferentes períodos de tempo. No geral, os resultados demonstraram que a atividade antimicrobiana de todos os medicamentos testados foi retardada na presença de soro ou de tecido necrosado. As pastas de hidróxido de cálcio em glicerina ou clorexidina foram significativamente afetadas pelo soro. Dos medicamentos testados, o menos afetado foi a pasta de hidróxido de cálcio/paramonoclorofenol canforado/glicerina.

Usefulness of Frozen-thawed-deglycerolized Red Blood Cells as Quality Control Materials for Red Blood Cell Deformability Test / 대한진단검사의학회지

BACKGROUND: The red blood cell (RBC) deformability test is a useful method for measuring the ability of RBCs to adapt their shape to the flow conditions. Using this test, several investigators have shown the relationship between RBC deformability and numerous clinical conditions. For the quality control (QC) of RBC deformability test, we evaluated whether frozen-thawed-deglycerolized RBCs can be used as QC materials. METHODS: Packed RBCs were frozen with 40% (wt/vol) glycerol and stored at -80degrees C for 3 months. For 10 different frozen RBC panels, RBCs were thawed, deglycerolized and stored at 4degrees C for 4 weeks. Using microfluidic ektacytometer, we measured RBC deformability of the thawed RBCs. The stability of thawed RBCs was tested once a day for 28 days of storage time and was analyzed by simple regression analysis. The precision of the test using thawed RBCs was analyzed for 7 days of storage time by calculation of CV values of intra-assay (10 measurements/assay) and between-day measurements. RESULTS: Frozen-thawed-deglycerolized RBCs were stable for 1 week. Within-run and between-day precisions of the RBC deformability test during 7 days of storage of thawed RBCs were 1.4-2.9%, and 1.9-2.8%, respectively. CONCLUSIONS: Frozen-thawed-deglycerolized RBCs used in RBC deformability test showed satisfactory within-run and between-run precisions and stability for one week after thawing, and may be used as QC materials for this test.

Comparative study of cryopreserved bone tissue and tissue preserved in a 98 percent glycerol solution / Estudo comparativo entre o tecido ósseo criopreservado e o conservado em glicerol a 98 por cento

OBJECTIVE: To compare the bone graft cryopreservation method (at -80°C) with a preservation method using a 98 percent glycerol solution at room temperature (10°C-35°C), by testing the antibacterial and fungal effects of 98 percent glycerol and comparatively analyzing the observed histological changes resulting from the use of both methods. METHOD: This study was of 30 samples of trabecular bone tissue from 10 patients undergoing total hip arthroplasty. Each femoral head provided 3 samples that were randomized into 3 groups, namely, the control group, the cryopreserved group, and the group preserved in a 98 percent glycerol at room temperature for 1 year. The samples were submitted to histomorphologic, cell feasibility, and microbiologic analyses. The results were statistically analyzed using the McNemar test, with a statistical significance index of 0.05. RESULTS: Values obtained using the McNemar test to compare probability distributions of histomorphologic variables (mature or lamellar bone, immature bone, and necrosis) and cell feasibility (osteoblasts and osteoclasts) indicated that there is no difference between the distributions of variables under the 3 experimental conditions. Microbiological analysis of the 98 percent glycerol solution and bone fragments from samples stored for 1 year at room temperature did not show bacterial or fungal growth. The histological and microbiological investigation were performed at 2 different time points: immediately after the sample processing and after 1 year. CONCLUSION: The method used to preserve bone grafts kept in 98 percent glycerol at room temperature (10°C-35°C) was similar to cryopreservation in terms of bone matrix preservation; no bacteria or fungi were found in the samples.

OBJETIVO: Comparar o método da criopreservação de enxertos ósseos (- 80° C) com o da conservação em glicerol a 98 por cento em temperatura ambiente (10° C a 35° C), testando os efeitos antibacterianos e antifúngicos do glicerol a 98 por cento e analisando comparativamente as alterações histológicas verificadas e decorrentes do emprego dos dois métodos. MÉTODO: Este estudo foi constituído de 30 amostras de tecido ósseo trabecular provenientes de 10 pacientes, submetidos a Artroplastia Total do Quadril. Cada cabeça femoral forneceu 3 amostras e estas foram divididas aleatoriamente em 3 grupos, a saber: controle, criopreservado e conservado em glicerol a 98 por cento à temperatura ambiente durante um ano. As amostras foram encaminhadas à Anatomia Patológica para estudo histomorfologico, de viabilidade celular, e microbiológico. Os resultados foram analisados estatisticamente pelo método de McNemar, com índice de significância de 0,05. RESULTADOS: A análise dos valores obtidos no teste de McNemar na comparação das distribuições de probabilidades das variáveis da histomorfologia (osso maduro ou lamelar, osso imaturo e necrose) e da viabilidade celular (osteoblastos e osteoclastos) indica não haver diferença entre as distribuições das variáveis nas três condições experimentais. A análise microbiológica da solução de glicerol a 98 por cento e dos fragmentos ósseos das amostras armazenadas durante um ano em temperatura ambiente não apresentou crescimento bacteriano ou de fungos. As espécimens do grupo controle foram analisadas histológica e microbiologicamente logo após a coleta das mesmas. CONCLUSÃO: O método de conservação de enxertos ósseos mantidos no glicerol a 98 por cento em temperatura ambiente (10°C a 35°C) foi similar ao da criopreservação quanto à preservação da matriz óssea e à ausência de crescimento de bactérias ou fungos.