Analysis of the Frequency of morphological defects produced on the active surface of Biorace and Protaper Next instruments after repeated use

Abstract

To analyze the frequency of morphological defects available on the active surface of different Biorace and Protaper Next instruments after repeated uses through scanning electron microscopy (SEM). Thirty replicas of prototyped mandibular molars were randomly distributed into two groups (n = 15) according to the rotational system used: G1. Biorace^®; G2. Protaper Next^®. After preparation, all instruments were washed in an ultrasonic vat and finished with SEM images of 50x and 1000x images to visualize morphological changes regarding the presence of blunting of edges, grooves, microcavities and cracks. To determine the defects on the instrument surface, the active part was divided into 14 parts considering the two sides named segments 1 to 7. The frequencies of defects found for each segment of the instruments in each group were crossed with the data of the number of instruments through the Chi-square test. As for the frequency of defects, there was no difference when comparing the instruments of each system. When comparing the Biorace® and Protaper Next® groups, there was a statistically significant difference (p < 0.05). All instruments in the groups dissipated onto the active surface after repeated use.