Shaping Ability of the ProTaper Gold and R-Motion Systems in Long-Oval Canals: A Microcomputed Tomography Study.

Objectives:The aim of this study was to evaluate, by microcomputed tomography (micro-CT), the shaping ability and reduction of dentin thickness in mesial and distal surfaces of the ProTaper Gold (PTG; Dentsply Sirona, Ballaigues, Switzerland) and R-Motion (RM; FKG Dentaire, La Chaux-de-Fonds, Switzerland) systems in long-oval canals of lower incisors. Materials and Methods: Twenty long-oval lower incisors were selected, compared anatomically, and scanned by micro-CT (SkyScan 1172, Bruker Micro-CT, Kontich, Belgium). The teeth were divided into two groups (n = 10) according to instrumentation technique: PTG and RM. The following morphometric measurements were made on images recorded before and after preparation: volume, surface area, structure model index (SMI), unprepared walls, and dentin thickness parameters were calculated. The Shapiro-Wilk test and Student t-test were used for comparison of the data between the two groups at a significance level of 5%. Results: Significant differences were found in volume (127.60% vs. 69.22%) and reduction in dentin thickness on the distal surface of the root canal, with higher values for PTG compared to RM, respectively (p < 0.05). There was no significant difference in surface area (34.79% vs. 26.93%), SMI, and the percentage of unprepared areas (9.43% vs. 12.22%). Conclusion: Although GTP resulted in a greater reduction in dentin thickness on the distal surface and volume, there was no difference in the percentage of contact surface and unprepared areas between the two systems, confirming that neither technique was able to completely prepare the long-oval canals of the lower incisors. Clinical Relevance: Despite the technological advances in instruments launched on the market, exhibiting greater flexibility due to their metallurgical properties and short sequences, there is little scientific evidence regarding the new RM instrument, manufactured by FKG Dentaire, and its root canal modeling capacity.