Abstract: Objective: To investigate the effect of phytic acid (inositol hexakisphosphate,IP6), as a root canal chelating agent on the smear layer and the chemical composition of dentin treated with sodium hypochlorite (NaClO). Methods: Twenty-four intact dentin specimens from the crown of premolars were randomly assigned into four groups (n=6) and treated with 2 mL deionized water (5 min), 2mL 5% NaClO (5 min), 2mL 5% NaClO (5 min) followed by 2mL 17% EDTA or 1% IP6 (1 min). The presence of smear layer was evaluated with scanning electron microscopy (SEM). The dentinal infrared spectrum was recorded by attenuated total reflection infrared(ATR-IR) spectrometer. M:M(matrix:mineral)and C:M(carbonated:mineral) were calculated and analyzed by two-way RMANOVA. Results: The SEM images showed that 5% NaClO followed by 17% EDTA or 1% IP6 almost removed the smear layer completely, while DW and 5% NaClO alone left a large number of smear layer. It revealed that M:M remained unchanged in group DW (p=0.744), but it decreased significantly in group 5% NaClO alone or followed by 17% EDTA or 1% IP6 (P<0.01). M:M of the latter three groups was obviously lower than that of group DW (P<0.01), and there was no significant difference among the three groups (P>0.05). C:M decreased