Abstract: Objective: To evaluate the penetration depth of iRoot SP in the dentinal tubules by scanning electron microscopy (SEM). Methods: Twenty-eight mandibular premolars with single canal were decoronated to obtain 14-mm root segments. The root canals were instrumented using Protaper files prepared to F1. Roots were randomly divided into 2 experimental groups (A and B, n=12) and control group (n=4). Specimens of group A were filled with iRoot SP using the continuous wave of condensation technique. Specimens of group B were filled with AH Plus using the same technique. Specimens of group A and group B were transversely sectioned. The sealers penetration depth into the dentinal tubules was observed and measured in the coronal, middle and apical third of the root canal using SEM. Specimens of control group were longitudinally sectioned and the dentinal tubules were observed. Results: The penetration depth of AH Plus group was significantly higher than that of iRoot SP group in the apical third of the root canal walls (P<0.05). There was no significant difference in the coronal and middle third of the root canal walls between two groups. The smear layer was almost completely removed in the coronal and middle third of the root canal walls, however, partly removed in the apical third of the root canal walls. Conclusion: The dentinal tubule penetration of AH Plus is significantly greater than that of iRoot SP. The penetration depth of AH Plus and iRoot SP was better in the coronal and middle third than in the apical third of the root canal walls. The dentinal tubule penetration of sealers is affected by their physical and chemical properties and smear layer.

Key words: iRoot, SP, Permeability , Scanning electron microscopy