During instrumentation of a root canal, ethylene diamine tetraacetic acid (EDTA) as a chelating agents may be used during cleaning and shaping. EDTA demineralizes dentin and may inadvertently contribute to root canal transportation. The purpose of this study was to evaluate the effect of chelating agents used in moderately curved canals during instrumentation using micro-computed tomography (μCT) and imaging/modelling technology. Methods: Moderately curved root canals of 36 identified mandibular premolars were standardized in length and divided into 3 groups (n=12). Initial scans were taken using μCT. All canals were instrumented with Profile® DENTSPLY0.06 taper NiTi rotary instruments using saline, 17% EDTA (Pulpdent Corp., Watertown, MA) or RC Prep™(Premier). After instrumentation, lengths were re-measured and all the teeth were re-scanned. Using computer software, 3-dimensional models were created from the pre and post-instrumentation scans. Models were compared for changes in volume and transportation. Results: There was no statistically significant difference between the groups for any of the variables evaluated: working length , volume and transportation. Conclusion: Under the conditions of this study, the use of chelating agents during instrumentation did not affect the size or position of the root canals.