The aim of the present in vitro study was to compare the apical sealing ability of a warm vertical condensation system (EndoTwinn) with lateral condensation and Thermafil using two resin-based sealers (AH Plus, EndoRez). Sixty extracted single rooted incisors stored in saline were used. Each tooth was endodontically prepared using the Hero 642 system to a maximum size of 40. Working length was recorded 1 mm shorter than the anatomical apex. All teeth were randomly assigned to six experimental groups of nine each. Root canal fillings were performed using either warm vertical condensation (V), Thermafil obturators (T) or cold lateral condensation (L) with EndoRez (E) or AH Plus (A) as sealer. After root canal filling, the teeth were coated with nail varnish, leaving the apical foramen exposed and stored in 5% methylene blue solution for seven days. The apical 1 mm of each tooth was removed to reveal the apical limit of preparation. Four transverse sections of the teeth were taken at each millimetre from this point. The distribution of filling material in each canal was assessed by stereomicroscopic examination and areas of sealer (S), gutta-percha (G) and voids (V) were measured on the digital images. Statistical analysis was performed using ANOVA and Tukey's test. The total area of gutta-percha was not statistically different among the different obturation techniques (p Schlagwörter: endodontics, root canal obturation, resin-based sealers