Comparison Of Different Root Filling Techniques Using A Glass Ionomer Sealer O. Graefen*, A. Braun, R. Nolden, M. Frentzen (University Dental Clinic, Department of Operative Dentistry and Periodontology Welschnonnenstraße 17, D-53111 Bonn, Germany) The aim of the study was to compare the density of root canal fillings using a glass-ionomer sealer (Endion‘) and a zink oxide eugenol sealer (Tubliseal‘) comparing different application techniques. The root canals of 60 human extracted teeth were prepared up to size 40 in a step back technique (two steps) and divided into two groups of 30 teeth each (glass-ionomer sealer and zink oxide eugenol sealer). In each group always 10 teeth were filled with different techniques (paste filling, central cone technique, lateral condensation). All teeth were stored in a physiological saline solution. After coating the root surface with nail polish, leaving the apical area uncovered, the teeth were immersed in India ink for 24 hours. To measure the dye penetration depth, the teeth were demineralized, cleared in methyl salicylate and examined with a light microscope. Analysis of variance (ANOVA) with subsequent Scheffé-test (α = 0,05) were used for statistical analysis of the ink penetration depth. Regarding the zinc oxide sealer (used with lateral condensation and central cone technique) the ink-penetration values were statistically significant lower than those related to the glass ionomer sealer (applied with the paste-filling and the central cone technique). Using TubliSeal‘ statistically significant higher penetration values appeared with the paste filling technique compared with lateral condensation and central cone technique.   The present study indicates that apical density of root canal fillings can not be increased using a glass ionomer sealer, compared to a zinc oxide sealer. A paste-filling should neither be done with a glass ionomer sealer nor with a zinc oxide sealer.