Cyclic fatigue life of novel rotary compactors: A scanning electron microscopy evaluation

The aim was to investigate the cyclic fatigue life of two novel rotary compactors produced for MTA compaction and produced for gutta-percha compaction. Two-type of nickel-titanium rotary compactors were used (n = 20). A static model was preferred for this study due to simulating the clinical application of compaction and to obtain a baseline repository data of this type of instruments. OrthoMTA Compacter (25/0.02) and Revo Condensor (30/0.04) instruments were operated speed of 250 and 4,800 rpm, respectively at 35°C until fracture occurred. The time to fracture was recorded, and the length of the fractured fragments was registered. The independent t-test was performed (p < .05). The fractured instruments were evaluated with a high-resolution field emission scanning electron microscope to allow visualization of the surfaces under several magnifications (×100 and ×10,000). OrthoMTA Compacter (3679.27 NCF), was extremely different in the mean number of cycles to failure when compared with Revo Condensor (1269.48 NCF) (p < .0001). The mean length of the fractured tip of OrthoMTA Compacter and Revo Condensor were 4.87 mm and 4.51, respectively (p < .0001). The surfaces of the instruments shown typical features of cyclic fatigue failure, involving crack origins, fatigue regions, and an overload region. This is the first study in the literature to date evaluating the cyclic fatigue life of Revo Condensor and OrthoMTA Compacter. OrthoMTA Compacter presented higher cyclic fatigue life compared with Revo Condensor.