Bond strength of experimental root canal sealers based on mta and butyl ethylene glycol disalicylate

Abstract This study investigated the bond strength of two experimental root canal sealers based on MTA and butyl ethylene glycol disalicylate: MTAe and MTAe-HA. The reference materials used for comparison were AH Plus and MTA Fillapex. Twenty human upper incisors were selected and one 1 mm slice was obtained from the cervical third of each root. On the coronal surface of each slice, four 0.9 mm wide holes were drilled through the dentine. Standardized irrigation was performed and holes were filled with one of the four tested sealers: AH Plus, MTA Fillapex, MTAe, and MTAe-HA. The filled slices were stored in a PBS solution (pH 7.2) for 7 days at 37 °C. A push-out assessment was performed with a 0.7 mm plunger tip. Load was applied at a crosshead speed of 0.5 mm/min until sealer displacement. The results were expressed in MPa. The Kruskal-Wallis test was applied to assess the effect of each sealer on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. Significant differences among medians values obtained by materials were observed (p<0.001). AH Plus displayed the highest value of bond strength (p<0.001). In contrast, MTA Fillapex presented the lowest bond strength among all tested sealers (p<0.001). Experimental sealers showed intermediary bond strength values, with no statistical differences between them (p>0.05). In conclusion, experimental root canal sealers presented suitable bond strength outcomes when compared to MTA Fillapex.

Resumo Esse estudo investigou a resistência de união de dois cimentos endodônticos experimentais à base de MTA e butiletilenoglicol dissalicilato: MTAe e MTAe. Os materiais de referência utilizados para comparação foram os cimentos endodônticos MTA Fillapex e AH Plus. Vinte incisivos superiores humanos foram selecionados e um slice dentinário de 1 mm de espessura foi obtido do terço cervical de cada raiz. Na superfície coronária de cada slice, quatro orifícios com 0,9 mm de diâmetro foram confeccionados através da dentina. Uma irrigação padronizada foi realizada e os orifícios foram preenchidos com um dos quatro cimentos endodônticos avaliados: AH Plus, MTA Fillapex, MTAe, e MTAe-HA. Os slices preenchidos foram armazenados em solução PBS (pH 7,2) durante 7 dias a 37°C. O ensaio de push-out foi realizado por meio de um dispositivo com 0,7 mm de diâmetro. A carga foi aplicada com a velocidade de 0,5 mm/min até a obtenção de deslocamento do material obturador. Os resultados foram expressos em MPa. O teste de Kruskal-Wallis foi aplicado para avaliar o efeito da resistência de união de cada cimento endodôntico. O teste de Mann-Whitney com correção de Bonferroni foi utilizado para isolamento das diferenças. O erro do tipo-alfa foi fixado em 0,05. Diferenças significantes entre os valores de medianas obtidos pelos materiais foram observados (p<0,001). O AH Plus demonstrou os maiores valores de resistência de união (p<0,001). Em contraste, o MTA Fillapex apresentou a menor resistência de união entre todos os cimentos testados (p<0,001). Os cimentos experimentais demonstraram valores intermediários, com ausência de diferenças estatísticas entre si (p>0,05). Em conclusão, os cimentos endodônticos experimentais à base de MTA e butiletilenoglicol dissalicilato apresentaram resultados adequados de resistência de união quando comparados ao MTA Fillapex.

Independent and Interactive Influences of the APOE Genotype and Beta-Amyloid Burden on Cognitive Function in Mild Cognitive Impairment

This study aimed to investigate the independent and interactive influences of apolipoprotein E (APOE) epsilon4 and beta-amyloid (Abeta) on multiple cognitive domains in a large group of cognitively normal (CN) individuals and patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Participants were included if clinical and cognitive assessments, amyloid imaging, and APOE genotype were all available from the Alzheimer's Disease Neuroimaging Initiative database (CN = 324, MCI = 502, AD = 182). Individuals with one or two copies of epsilon4 were designated as APOE epsilon4 carriers (epsilon4+); individuals with no epsilon4 were designated as APOE epsilon4 non-carriers (epsilon4-). Based on mean florbetapir standard uptake value ratios, participants were classified as Abeta burden-positive (Abeta+) or Abeta burden-negative (Abeta-). In MCI, APOE epsilon4 effects were predominantly observed on frontal executive function, with epsilon4+ participants exhibiting poorer performances; Abeta positivity had no influence on this effect. Abeta effects were observed on global cognition, memory, and visuospatial ability, with Abeta+ participants exhibiting poorer performances. Measures of frontal executive function were not influenced by Abeta. Interactive effects of APOE epsilon4+ and Abeta were observed on global cognition and verbal recognition memory. Abeta, not APOE epsilon4+, influenced clinical severity and functional status. The influences of APOE epsilon4+ and Abeta on cognitive function were minimal in CN and AD. In conclusion, we provide further evidence of both independent and interactive influences of APOE epsilon4+ and Abeta on cognitive function in MCI, with APOE epsilon4+ and Abeta showing dissociable effects on executive and non-executive functions, respectively.

Micelle formation in water-ethylene glycol mixtures

Critical micelle concentrations [cmc's] of the ionic surfactant dodecyltriethanolammonium iodide have been studied spectrophotometrically in water-ethylene glycol [EG] mixtures [XEG = 0.0, 0.093, 0.120, 0.290, 0.552 and 1 at 25, 35 and 45C]. The equilibrium model of micelle formation is selected to determine the thermodynamic parameters delta G, delta H and delta S. An interpretation of structural changes in H2O-EG system has been suggested