The purpose of this study was to evaluate the apical sealing ability ofthree different obturation techniques by using a dye leakage test；to findwhether the use of GuttaFlow, or the E & Q Plus System creates a better sealthan cold lateral condensation technique；by comparing the dye leakage inroot canals filled with each of them；and to statistically analyze theobtained data to come to a conclusion.Study design:One hundred and thirty extracted single-rooted maxillary anteriorswere selected for the study.The teeth were decoronated and the root canalsprepared using ProFile rotary instruments to an apical dimension of size 40(0.06 taper). The specimens were then randomly divided into threeexperimental groups (n=40) and filled with gutta-percha and AH Plussealer by using either cold lateral compaction or the E & Q Plus system;and GuttaFlow respectively. Another five teeth each served as the positiveand negative controls. A dye leakage test was used for quantitativeevaluation of the apical microleakage at ten days, one month, six monthsand one year；using a stereomicroscope.Results:1. No significant difference in the cumulative amount of leakage wasfound among the three groups at ten days (Kruskal-Wallis test, P>0.05).2. Lateral compaction showed significantly more leakage than the othertwo techniques at longer intervals (Kruskal-Wallis test, P<0.05).3. No significant difference was found between E & Q Plus andGuttaFlow at one and six months.4. However, GuttaFlow showed the best overall result over a oneperiod.Conclusion:1 .Problems associated with the inadequate seal formed by gutta-perchawhen used as an obturation material have been known for decades. Theexperiment has also shown us that no matter what kind of method wechoose, with the extension of time, the amount of microleakage increases.2. No significant difference in the cumulative amount of leakage wasfound among the three groups at ten days3. The E & Q Plus system and GuttaFlow showed a better sealing resultthan cold lateral compaction of gutta-percha at extended observationperiods；i.e., after ten days.4. GuttaFlow showed the best overall result over a one year period.All in all, with respect to the apical sealing ability, coldfluid gutta-percha (GuttaFlow) shows a better result；therefore, its usewould be worthwhile among practicing clinicians.5. Further case-controlled study, or better still, randomized clinical trialis needed if the various filling techniques are to be compared for theirclinical performance. Other needed research includes in vivo studiesshowing long-term success rates of these materials.