Micro–Computed Tomography Assessment of Dentinal Micro-cracks after Root Canal Preparation with TRUShape and Self-Adjusting File Systems

M.L. Zuolo, G. De-Deus, F.G. Belladonna, E.J.N.L. da Silva, R.T. Lopes, E.M. Souza, M.A. Versiani, A.A. Zaia

Journal of Endodontics 2017 Apr;43(4):619-622.


INTRODUCTION: The aim of the present study was to evaluate the percentage frequency of dentinal micro-cracks observed after root canal preparation with TRUShape and Self-Adjusting File (SAF) systems by means of micro–computed tomography imaging analysis. A conventional full-sequence rotary system (BioRace) and a single-file reciprocation system (Reciproc) were used as reference techniques for comparison because of their known assertive cutting efficiency.

METHODS: Forty anatomically matched mandibular incisors were selected, scanned at a resolution of 14.25 μm, and assigned to 4 experimental groups (n = 10), according to the preparation protocol: TRUShape, SAF, BioRace, and Reciproc systems. After the experimental procedures, the specimens were scanned again, and the registered preoperative and postoperative cross-section images of the roots (n = 70,030) were screened to identify the presence of dentinal micro-cracks.

RESULTS: Overall, dentinal defects were observed in 28,790 cross-section images (41.11%). In the TRUShape, SAF, BioRace, and Reciproc groups, dentinal micro-cracks were visualized in 56.47% (n = 9842), 42.38% (n = 7450), 32.90% (n = 5826), and 32.77% (n = 5672) of the slices, respectively. All dentinal defects observed in the postoperative data sets were already present in the corresponding preoperative images.

CONCLUSIONS: None of the preparation systems induced the formation of new dentinal micro-cracks.

Zuolo JOE 2017 microcracks


The full article is available on Researchgate

zuolo microcracks


Additional Info

  • ReDent Nova’s note:

    The main issue with this research is that micro-CT is not a good method to examine the creation of micro-cracks, since the method of examination itself, that involves drying of the roots during the lengthy scanning process, is likely to cause micro-cracks. This explains why the initial scans already present micro-cracks.

    Unsurprisingly, the Self-Adjusting File was found not to create microcracks. More surprisingly, the other instruments (Reciproc, BioRace, TRUShape) did not create microcracks either. 

    Reading the article clarifies that the authors made an effort to avoid the creation of microcracks, by choosing roots that were already cracked (an issue that reduces the chance for creation of new micro-cracks), and by using the smallest possible instruments of each brand, up to size #25. 

    Something else to notice are the micro-CT scans in this article, that reveal the keyhole preparations made by the rotary instruments (all other than the SAF) - excessive removal of sound dentin on one side, and significant uninstrumented parts on the other.

  • publisher: publisher
  • View abstract on PubMed. PMID: 28216274