Evaluation of the Incidence of Microcracks Caused by Mtwo and ProTaper NEXT Rotary File Systems versus the Self Adjusting File: A Scanning Electron Microscopic Study

S.G. Saha, N. Vijaywargiya, S. Dubey, D. Saxena, S. Kala

International Endodontic Journal. 2015 Nov 24. Epub ahead of publication


AIM: To evaluate the incidence of microcrack formation in roots following canal preparation with two rotary nickel titanium systems Mtwo and ProTaper NEXT along with the Self Adjusting File system.

METHODOLOGY: One hundred and twenty mandibular premolar teeth having straight roots with single canals extracted for orthodontic purposes from patients of mean age group 17-25 years were selected. Standardized access cavities were prepared and the canals were manually prepared up to size 20 after coronal preflaring. The teeth were divided into three experimental groups and one control group (n=30). Group 1: The root canals were prepared using Mtwo rotary files up to an apical diameter of 0.40 mm and 0.04 taper. Group 2: The root canals were prepared with ProTaper NEXT files up to an apical diameter of 0.40 mm and apical taper of 6.5%. Group 3: The root canals were prepared with Self Adjusting Files (1.5mm). Group 4: The root canals in this group were unprepared and used as a control. The roots were sectioned horizontally 3, 6 and 9 mm from the apex and examined under a scanning electron microscope to check for the presence or absence of cracks. The Pearson Chi-square test was applied.

RESULTS: The highest incidence of cracks were associated with the ProTaper NEXT group, 80% (P=0.00), followed by the Mtwo group, 70% (P=0.000) and the least number of cracks were noted in the Self Adjusting File group, 10% (P=0.068). No significant difference was found between the ProTaper NEXT and Mtwo groups (P=0.368), while a significant difference was observed between the ProTaper NEXT and Self Adjusting File groups (P=0.000) as well as the Mtwo and Self Adjusting File groups (P=0.000).

CONCLUSIONS: All nickel titanium rotary instrument systems were associated with cracks. However, the Self Adjusting File system had significantly fewer cracks when compared with the Mtwo and ProTaper NEXT.



Additional Info

  • ReDent Nova’s note:

    Several months after the publication, the article was retracted by the authors, due to issues in the SEM procedure that might cause the results to be inaccurate. This does not contradict the fact that the Self-Adjusting File was shown in this research to create less micro-cracks than Mtwo and ProTaper Next, with or without the deflection caused by the examination procedure.

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  • View abstract on PubMed. PMID: 26599835