Objective: The purpose of this laboratory-based study was to compare the shaping forces and torques developed by the XP Shaper (FKG Dentaire SA, La Chaux-de-fonds, Switzerland) and OneCurve (Micro-Mega, Besancon, France) systems during shaping of narrow canals. Methods: Mandibular premolars with a single canal were divided equally into two groups; XP Shaper and OneCurve (n=16 each). In both groups, the canals were shaped with XP Shaper file (30/01) or OneCurve file (25/O6) that was inserted three times until it reached the canal length. The tooth was surrounded by water under controlled simulated intracanal temperature throughout the experiment. The inward and outward peak forces and the peak torques were recorded and analyzed statistically using the Mann-Whitney test. The shaping times were analyzed using Student’s t-test. The significance level was set at 5%. Results: In both groups, the developed forces in both directions and the torques increased with the successive insertions of the file. In the two groups, the inward peak forces ranged from 0.33 to 3.12 N, while the outward peak forces ranged from 0.09 to 1.96 N. In the three insertions, the XP Shaper showed significantly lower peak forces in both directions. The peak torque developed in both groups ranged from 0.12 to 1.52 N.cm. XP Shaper had significantly lower torque values in all the insertions than OneCurve. The XP Shaper system was able to completely shape the canals in 33.4 seconds while the OneCurve system was able to completely shape the canals in 32.8 seconds. Conclusion: The XP Shaper system showed favorably lower force and torque values during canal shaping compared with the OneCurve system.

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Background The aim of this in vitro study was to evaluate the magnitude of shaping forces and dynamic torques developed with XP shaper (XPS) and OneCurve (OC) systems during canal shaping of extracted teeth.Methods Thirty-two single-canalled mandibular premolars were divided into two groups: XPS and OC (n=16 each). In XPS and OC, the canals were shaped with their dedicated file inserted three times until it reached the canal length. The experiment was performed while the test sample was surrounded by water under controlled simulated intracanal temperature. The real-time shaping forces and torques induced during canal shaping were observed. The inward and outward peak shaping forces and the peak torques were recorded and used for statistical analysis by using the Mann-Whitney test. The statistical significance was set at 5%.Results In both groups, the developed shaping forces in both directions and the torques increased with the successive file insertions. The inward and outward peak forces of the XPS and OC groups ranged from 0.33 to 3.12 N and from 0.09 to 1.96 N, respectively. The peak torque developed in both groups ranged from 0.12 to 1.52 N.cm. In the three insertions, the XPS showed significantly lower peak forces in both directions (P=0.00). For the peak torque, XPS had significantly lower values in all the insertions (P=0.00).Conclusions The XPS system had significantly lower shaping forces and lower dynamic torque values during canal shaping compared with the OC system.