RESUMEN
AIM: This randomized, controlled trial evaluated the incidence of postinstrumentation pain on using two different rotary Ni-Ti and one reciprocating Ni-Ti cleaning and shaping systems. MATERIALS AND METHODS: Asfter sample size estimation, a total of 152 patients were randomized to three groups (Group WO [WaveOne], Group PU [ProTaper Universal], and Group Mt [Mtwo]). Selection of patients was based on root curvature, periapical lesion, vitality, gender, and diagnosis of the patient. A similar clinical protocol was followed and endodontic treatment was performed. Pre- and post-instrumentation pain scores (2, 4, 6, 8, 12, 36, and 48 h) were recorded using visual analog scale score. Kruskal-Wallis test was done for overall comparison of the groups. Bonferroni-corrected Mann-Whitney test was done for pair-wise comparisons and Friedman test was done to compare pain between time points in each file system (P < 0.05). RESULTS: All preinstrumentation pain values were higher than postinstrumentation pain values (P < 0.05). At 48 h, patients in Group WO experienced more pain compared to the other two groups. Pain scores of nonvital teeth were significantly higher when compared to vital teeth. Among nonvital teeth, patients in Group WO had early onset of pain at 6 h and lasted till 48 h, whereas pain started at 12 h and lasted till 36 and 48 h for Group Mt and Group PU, respectively. CONCLUSION: Patients treated with WaveOne files experienced more pain when compared to the other files. Nonvital teeth experienced more pain compared to vital teeth. Group Mt had the lowest postinstrumentation pain.
RESUMEN
OBJECTIVE: The purpose of this study was to assess the role of cross section on cyclic fatigue resistance of One Shape, Revo-S SU, and Mtwo rotary files in continuous rotation and reciprocating motion in dynamic testing model. MATERIALS AND METHODS: A total of 90 new rotary One Shape, Revo-S SU, and Mtwo files (ISO size 25, taper 0.06, length 25 mm) were subjected to continuous rotation or reciprocating motion. A cyclic fatigue testing device was fabricated with 60° angle of curvature and 5 mm radius. The dynamic testing of these files was performed using an electric motor which permitted the reproduction of pecking motion. All instruments were rotated or reciprocated until fracture occurred. The time taken for each instrument to fracture was recorded. All the fractured files were analyzed under a scanning electron microscope (SEM) to detect the mode of fracture. Statistical analysis was performed using one-way ANOVA, followed by Tukey's honestly significant difference post hoc test. RESULTS: The time taken for instruments in reciprocating motion to fail under cyclic loading was significantly longer when compared with groups in continuous rotary motion. There was a statistically significant difference between Mtwo rotary and the other two groups in both continuous and reciprocating motion. One Shape rotary files recorded significantly longer duration to fracture resistance when compared with Revo-S SU files in both continuous and reciprocating motion. SEM observations showed that the instruments of all groups had undergone a ductile mode of fracture. CONCLUSION: Reciprocating motion improved the cyclic fatigue resistance of all tested groups.