Influencia de diferentes intensidades de luz en la resistencia de unión de un sistema adhesivo utilizando un colorante fluorescente para su observación

The purpose of this study was to use a fluorescent dye and CLSM microscope to observe the effect of different light intensities on dentin tensile bond strength. Flat dentin surfaces were created on 16 intact human third molars and divided in 4 groups: Group G1 - halogen - KM -200R®; Group G2 - LED - Ultraled®; Group G3 - LED - UltraLume LED5® and Group G4 - LED - Biolux Single V®. For all the groups, the restoration procedure used Single Bond® adhesive, mixed with rodamin B and InTen-S® composite resin. Then, they were cut on serial sections to obtain 1 mm2 area and submitted to micro tensile test and after words, the fractures were analyzed with a digital microscope and CLSM. The statistical analysis showed that all in all groups, except Group G2, which had a significant smaller tensile bond strength ratio. The fracture mode analysis showed that there were significant differences when comparing groups G1 / G2, and G2 / G4. There is no evidence of relevant differences among the other groups. With these results, we conclude that the use of fluorescent dye and CLSM demonstrated to be a simple and nondestructive technique, and that there are evidences that light intensities influenced the dentine tensile.

Un uso de la historia en la enseñanza de la didáctica de la Física

It is shown the result of design, implement and analyze an exercise for teaching of Didactics of Physics, based on the use of History of Science as an information resource and point of discussion. We start with two assumptions: (1) currently, in the international level there is a research field that studies the use of History, Philosophy and Epistemology of sciences on education of teachers, which present that this field allows to treat contents of Physics in nontraditional ways, that is to say, beyond to the mathematician vision; (2) one of the dimensions that should be worked on education of teachers, specifically in education for teaching, must be, the (re) connaissance of their disciplinary knowledge, through metacognitive exercises, for which History provides appropriate resources. In order to involve the future teacher in a metacognitive activity that would allow (re) visit some of their knowledge of Physics, we developed an exercise based on research results about the history of the light concept. We analyzed the potentialities of this exercise to educate for teaching.