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Restor Dent Endod. 2018 May;43(2):e25. English. Original Article. https://doi.org/10.5395/rde.2018.43.e25
Pedullà E , Lo Savio F , La Rosa GR , Miccoli G , Bruno E , Rapisarda S , Chang SW , Rapisarda E , La Rosa G , Gambarini G , Testarelli L .
Department of General Surgery and Surgical-Medical Specialties, University of Catania, Catania, Italy. g_larosa92@live.it
Industrial Engineering, University of Catania, Catania, Italy.
Department of Endodontics, La Sapienza University, Rome, Italy.
MATIS IMM-CNR and Department of Physics, University of Catania, Catania, Italy.
Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, Seoul, Korea.
Abstract

Objectives

To evaluate the mechanical properties and metallurgical characteristics of the M3 Rotary and M3 Pro Gold files (United Dental).

Materials and Methods

One hundred and sixty new M3 Rotary and M3 Pro Gold files (sizes 20/0.04 and 25/0.04) were used. Torque and angle of rotation at failure (n = 20) were measured according to ISO 3630-1. Cyclic fatigue resistance was tested by measuring the number of cycles to failure in an artificial stainless steel canal (60° angle of curvature and a 5-mm radius). The metallurgical characteristics were investigated by differential scanning calorimetry. Data were analyzed using analysis of variance and the Student-Newman-Keuls test.

Results

Comparing the same size of the 2 different instruments, cyclic fatigue resistance was significantly higher in the M3 Pro Gold files than in the M3 Rotary files (p < 0.001). No significant difference was observed between the files in the maximum torque load, while a significantly higher angular rotation to fracture was observed for M3 Pro Gold (p < 0.05). In the DSC analysis, the M3 Pro Gold files showed one prominent peak on the heating curve and 2 prominent peaks on the cooling curve. In contrast, the M3 Rotary files showed 1 small peak on the heating curve and 1 small peak on the cooling curve.

Conclusions

The M3 Pro Gold files showed greater flexibility and angular rotation than the M3 Rotary files, without decrement of their torque resistance. The superior flexibility of M3 Pro Gold files can be attributed to their martensite phase.

Copyright © 2019. Korean Association of Medical Journal Editors.