comparison of apical sealing ability of two phases of gutta–percha: a bacterial leakage model

objectives : the aim of this study was to compare apical sealing ability of alpha and beta phases of gutta-percha by means of bacterial leakage model. materials and methods: fifty single-rooted human premolars were selected. the root canals were prepared with mtwo rotary instruments up to apical #35.04. forty teeth were randomly divided into two groups (n= 20). the root canals were obturated by alpha phase (g1) and beta phase (g2) of gutta-percha and ah26 sealer, respectively, with warm vertical compaction technique. ten teeth served as positive (n=8) and negative (n=2) control groups. then, the specimens were sterilized with ethylene oxide gas. bacterial suspension of enterococcus faecalis (e. faecalis) in 0.5 mcfarland concentration was prepared. all teeth were mounted in plastic vial caps containing muller hinton broth and then exposed to bacterial suspension of e. faecalis every three days up to 31 days. the number of days required for the contamination of the entire root canals was recorded. the data were analyzed using mann whitney u test. results: there were no significant differences in bacterial leakage between the g1 and g2 groups (p>0.05). negative controls revealed no microbial leakage; whereas positive controls showed gross microbial leakage. conclusion: despite better thermal conduction and adaptability of alpha phase of gutta-percha, our study revealed no significant difference in bacterial leakage between alpha and beta phases of gutta-percha in warm vertical compaction.