Cyclic fatigue resistance and shaping ability of a new reciprocating instrument

Resumo

This study evaluated the cyclic fatigue resistance and the volumetric changes in the root canal after preparation with R-Plus+ and Reciproc Blue instruments. Material and methods: A total of 12 instruments (n=6) were used for cyclic fatigue testing: R-Plus+ 25/.08, 40/.05 and Reciproc Blue 25/.08, 40/.05. The instruments were tested in an apparatus simulating a 60º curvature 5 mm of radius, with fracture times measured using a digital stopwatch and video recording. Fractured instruments were analyzed using scanning electron microscopy (SEM). For root canal volumetric change, 18 acrylic blocks with 60º curvature were prepared (n=9). Pre- and post-preparation scans were performed using micro-CT, and canal volume changes were calculated using CTan software. Data were analyzed by unpaired and paired t-tests (P=0.05). Results: The R-Plus instruments (sizes 25 and 40) showed significantly longer times to fracture due to cyclic fatigue compared to the Reciproc Blue instruments (P0.05). Conclusion: The R-Plus+ instruments demonstrated superior cyclic fatigue resistance compared to Reciproc Blue, with significantly longer times to fracture. However, both systems showed similar root canal volumetric changes after preparation.