MIHAELA VALENTINA CIRDEI, DALIANA MOCUTA, EMILIA OGODESCU, ANA PETCU, ANDREEA LAZEA, CARMEN TODEA EVALUATION OF MARGINAL PERCOLATION OF THE GLASS IONOMER FILLINGS AT TEMPORARY TEETH The purpose of this in vitro study is to evaluate the marginal percolation-micro leakage by comparing the possible infiltration of ionomer cement filling which was used to restore a class I cavity prepared by classic conventional method – diamond bur versus Er:YAG laser irradiation treatment. Ten molars were included in this study. The molars were random divided in two groups: group 1 - laser treatment and group 2- classic conventional treatments. The teeth were immersed in methylene blue solution for 24 h. Afterwards, the molars were vestibulo-oral sectioned through the centre of each restoration in order to see any signs of marginal percolation. The marginal percolation observed was more significant in conventional preparations group than in laser’s group. The glass ionomer cement remains one of the most adequate restorative materials to be used on deciduous molars when micro infiltration is questionable.