Long-Term Sealing Ability Of Various Gutta - Percha Root-Canal Filling Techniques J.G. De Moor Roeland* (Dept. Of Operative Dentistry And Endodontology, University Hospital,University Gent, Gent, Belgium) The long-term sealing ability of root-canal fillings is of clinical importance. The research confined to the evolution of the long-term sealing ability of root canal sealers in combination with different gutta-percha condensation and filling techniques is scarce. Therefore, the apical and coronal sealing ability of AH26 in combination with lateral condensation, vertical condensation, hybrid condensation, Thermafil and Soft-Core was investigated at three different time intervals. 454 single rooted teeth with mature apices were prepared chemome-chanically and divided into two groups of 227 teeth each. Each group of teeth was then subdivided in groups of 45 teeth (15 x 3) each and 2 control teeth. After storage in 100 % relative humidity at 37°C for 1 day, 1 week and 4 months, the apical and coronal leakage was determined using Indian ink. After 90 h of ink immersion each root was split longitudinally and the maximum extent of leakage was measured using a stereomicroscope at x6 magnification. Statistical analysis was done using Kruskal-Wallis test and Mann-Whitney test. As far as the apical leakage is concerned there was statistically significant more leakage in those teeth obturated with Soft-Core as compared to the other groups (p < 0.05).   As far as the coronal leakage is concerned the analysis of variance gives evidence of strong significant differences between groups on all three observation times (p < 0.001). Both Thermafil and Soft-Core leaked significantly more than the three other groups (p < 0.05).