Armita Rouhani - Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
Fateme Zoormand Ghasemi - General Dentist, Mashhad, Iran
Majid Akbari - Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
Shima Mosivand - Post Graduate Student of Endodontics, Mashhad University of Medical Sciences, Mashhad, Iran

Introduction: After endodontic procedures, root canal reinfection is a main concern for dentists. However, application of a proper apical seal can prevent such contamination. Therefore, it seems necessary to study the factors affecting the development of a suitable apical seal. Materials and Methods: In this study, 64 extracted human single-canal premolars were used. An equal length of roots was obtained by cutting the crown. The teeth were randomly divided into four experimental groups of 15 premolars, as well as 2 positive and negative controls. The root canal was manually prepared using K-file and step back method through canal filling by lateral compaction technique. In GP and GH groups, gutta-percha and AH 26 sealer were used to fill the canals, while Resilon and Epiphany sealer were used in RP and RH groups, respectively. Then, to prepare the post space, Peeso Reamer drill was used in GP and RP groups while heat carrier was applied in GH and RH groups to prepare the post space, respectively.  The coronal part of each root was contacted with enterococcus faecalis leachate in BHI medium and the root end was placed in the same culture medium. The samples were daily checked for turbidity in the lower culture medium for 90 days. The average duration of bacterial leakage between the groups wascompared using independent Student t-test. Results: All the positive control samples showed bacterial infiltration within 24 to 48 hours, while the negative control teeth remained uninfected during the test. Comparison of bacterial leakage rates between GP and GH groups showed no significant difference, which was similar to comparison results between RP and RH groups (P=0.549 and P=0.097, respectively). Comparison of bacterial leakage between GP and RP groups, as well as between GH and RH groups, showed a significant difference (P=0.018 and P<0.001, respectively), so that the average duration of leakage was significantly longer in the teeth obturated with gutta-percha/AH26 than with Resilon/Epiphany. There was a significant difference in root canal filler material regardless of the post space development method, i.e. heat carrier and Peeso Reamer (P<0.001). Conclusion: Considering the results of this study, the use of gutta-percha as a root filling material results in a better apical seal than Resilon. Application of heat carrier and Peeso Reamer showed no significant difference in effectiveness on the apical seal.    

Apical Seal, Gutta-percha, Resilon, Bacterial Leakage