This study assessed the frequency of dentinal microcracks using a cadaver mandible model in teeth instrumented with TRUShape (TS; Dentsply Sirona, York, PA), WaveOne Gold (WO, Dentsply Sirona), or K-files (KF) compared with an uninstrumented control group (CG).Methods
Fifteen human mandibles with 95 single-rooted teeth were randomly distributed into the following groups: CG (no preparation, n = 11), TS (n = 28), WO (n = 28), and KF (step-back preparation with K-Flex-o-files [Dentsply Sirona], n = 28). Teeth were prepared to apical sizes of #25/.06 or #25/.07; overlying bone was removed, and then teeth were lifted out of the socket and sectioned at 3, 6, and 9 mm from the apex using a low-speed saw. Resulting slices were photographed at 20× and 25× magnification. Three independent and blinded evaluators assessed the images for the presence of dentinal microcracks and their extension, direction, and location. The chi-square test was used for statistical analysis (P < .05).Results
In the final sample of 83 teeth for the 4 groups, microcracks were found in 10 of 33, 13 of 66, 16 of 69, and 21 of 81 sections for CG, TS, WO, and KF, respectively. There were no significant differences in the frequency of microcracks among the CG, TS, WO, or KF instruments overall or when comparing section levels (3 mm [P = .9], 6 mm [P = .18], or 9 mm [P = .69], respectively, from the apex). There were also no significant differences in the extension, direction, or location of the dentinal microcracks among all groups (P > .05).Conclusions
There was no difference in the frequency of microcracks among the experimental groups instrumented with TS, WO, and KF or uninstrumented controls.