Abstracts Aim: This study aims to measure the effect of the lateral cutting efficiency of reciprocating and rotary NiTi files on the produced Intracanal Splitting Forces (ICSF) during root canal preparation. Materials and Methods: 48 mandibular anterior bovine teeth with straight roots were used to create 48 simulated premolar roots, and 26 enamel-dentin disks. The samples were divided into 2 testing groups (n=24 and n=13 respectively), and 2 file systems with similar heat treatment but different kinematics and file geometries and designs were tested for the ICSF induced during preparation and the possible effect of their ability to cut in dentinal discs. The files tested were WaveOne® Gold (WOG) and Pro-Taper GOLD™ (PTG). Tests were carried out on a custom-made platform under automated conditions. The data collected by the force gauge is in newtons (N), and the cutting efficiency was calculated by measuring the depth of cut produced in dentin in mm. Data analysis was carried out with the Kolmogorov-Smirnov test and OneWay ANOVA. Results: The splitting forces test was significantly higher in PTG group (S1) file when compared to other PTG and WOG files. The force generated in WOG strokes presented an ascending manner as the file went deeper apically. The cutting efficiency of PTG (F2) was significantly higher than WOG's primary file. However, no significant correlation between splitting force and file cutting efficiency was detected. Conclusions: WOG single reciprocating file produced significantly lower splitting force values with significantly less aggressive dentin cutting compared to PTG multi-sequence rotary files. File design, kinematics, depth of strokes, and the maximum diameter of each file at the coronal third in relation to canal diameter, may be influencing factors in generating splitting forces. Key Words: Bovine teeth, vertical root fracture (VRF), intra-canal splitting force (ICSF), cutting efficiency, wedging effect, root canal preparation, dentin, stress strain.