Comparación de la conductancia hidráulica dentinaria, de acuerdo al tiempo de aplicación de desensibilizantes con base de oxalatos

ABSTRACT. Introduction: an in vitro model was used to measure the hydraulic conductance in human dentin discs treated with oxalic acid for 15, 30 or 60 s maintaining the occlusive effect and measuring 7 and 14 days after application. Methods: 45 dentin discs measuring 1 mm thick were obtained from human third molars which were free of caries and in no occlusion; the samples were obtained from patients aged 16 to 30 years. Discs were sorted out into three study groups (n = 15) depending on the time of application of a commercial solution of oxalate-based dentin desensitizer (DD) (BisBlock®) which contains ˂ 5% oxalic acid of 1.5-1.8 pH: in group A the agent was applied for 15 s, in group B it was applied for 30 s, and in group C for 60 s. The hydraulic conductance of each disc was calculated after acid etching, which corresponds to the maximum permeability of discs (100%) after immediate application of oxalic acid, as well as seven and fourteen days of storage in saline solution. The statistical analysis was done with ANOVA test and post-hoc Games-Howell test. Results: 35,46 ± 23.41% in Group A, 36.34 ± 15.88% in Group B and 24.99 ± 14.99% in Group C, showing that the use of DD for 15, 30 or 60 s decreased permeability in a statistically significant manner (p <0.05). Conclusions: DD was effective in reducing hydraulic conductance regardless of application time, but this reduction was temporary only, since after seven days permeability returns to values close to those of baseline.

O clima em sua regulamentação político-econômica: o acordo de Copenhague - COP 15

We know that the Earth goes through natural cycles that influence its climate and the development of their societies. In recent decades, climate changes and nature began to call world attention to the unbridled exploitation that was carried by the current economic system, causing unrest among scientific, social, political and economic world. The theory that man causes a warming in global temperatures by the release of greenhouse gases made the headlines of major newspapers in the world. From there, it was only a matter of time before environmental concerns became ownership of capital by its excessive appropriation. The fear of nuclear threat by the bombs of Hiroshima and Nagasaki left in fanfare the world, which together with the devastating impact of the exploitation of man and nature gave birth to the Environmental Revolution, a way of trying to change the development patterns of the time and behavior of the population. However, based on the historical form of capitalist domination, this was another measure that was apossada the economic system being transformed into economic value and political exchange. The origin of the conventions, meetings, conferences, parliaments set up to discuss environmental issues, eventually became forums of political and economic talks focused on environmental governance, valuing an asset that is public and everyone. Environmental and climate issue now has a value, thus turning the agenda on the agenda of the United Nations (UN) for its political and economic regulation in the form of global agreement. Given the need for understanding the climate issue, was born the Conference of the Parties (COPs), a regulatory body for climate negotiations, surrounded interests, complexities, conflicts and disagreements between the parties countries, which becomes clear when we analyze their agreements...