Effect of reciprocating file motion on microcrack formation in root canals: an <scp>SEM</scp> study

<jats:title>Abstract</jats:title><jats:sec><jats:title>Aim</jats:title><jats:p>To compare dentinal microcrack formation whilst using <jats:styled-content style="fixed-case">N</jats:styled-content>i–<jats:styled-content style="fixed-case">T</jats:styled-content>i hand K‐files, <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper hand and rotary files and the <jats:styled-content style="fixed-case">W</jats:styled-content>ave<jats:styled-content style="fixed-case">O</jats:styled-content>ne reciprocating file.</jats:p></jats:sec><jats:sec><jats:title>Methodology</jats:title><jats:p>One hundred and fifty mandibular first molars were selected. Thirty teeth were left unprepared and served as controls, and the remaining 120 teeth were divided into four groups. <jats:styled-content style="fixed-case">N</jats:styled-content>i–<jats:styled-content style="fixed-case">T</jats:styled-content>i hand <jats:styled-content style="fixed-case">K</jats:styled-content>‐files, <jats:styled-content style="fixed-case">P</jats:styled-content>roTaper hand files, <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper rotary files and <jats:styled-content style="fixed-case">W</jats:styled-content>ave<jats:styled-content style="fixed-case">O</jats:styled-content>ne Primary reciprocating files were used to prepare the mesial canals. Roots were then sectioned 3, 6 and 9 mm from the apex, and the cut surface was observed under scanning electron microscope (<jats:styled-content style="fixed-case">SEM</jats:styled-content>) and checked for the presence of dentinal microcracks.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The control and <jats:styled-content style="fixed-case">N</jats:styled-content>i–<jats:styled-content style="fixed-case">T</jats:styled-content>i hand <jats:styled-content style="fixed-case">K</jats:styled-content>‐files groups were not associated with microcracks. In roots prepared with <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper hand files, <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper rotary files and <jats:styled-content style="fixed-case">W</jats:styled-content>ave<jats:styled-content style="fixed-case">O</jats:styled-content>ne Primary reciprocating files, dentinal microcracks were present. There was a significant difference between control/<jats:styled-content style="fixed-case">N</jats:styled-content>i–<jats:styled-content style="fixed-case">T</jats:styled-content>i hand <jats:styled-content style="fixed-case">K</jats:styled-content>‐files group and <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper hand files/<jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper rotary files/<jats:styled-content style="fixed-case">W</jats:styled-content>ave<jats:styled-content style="fixed-case">O</jats:styled-content>ne Primary reciprocating file group (<jats:italic>P</jats:italic> < 0.001) with <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper rotary files producing the most microcracks. No significant difference was observed between teeth prepared with <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper hand files and <jats:styled-content style="fixed-case">W</jats:styled-content>ave<jats:styled-content style="fixed-case">O</jats:styled-content>ne Primary reciprocating files.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p><jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper rotary files were associated with significantly more microcracks than <jats:styled-content style="fixed-case">P</jats:styled-content>ro<jats:styled-content style="fixed-case">T</jats:styled-content>aper hand files and <jats:styled-content style="fixed-case">W</jats:styled-content>ave<jats:styled-content style="fixed-case">O</jats:styled-content>ne Primary reciprocating files. <jats:styled-content style="fixed-case">N</jats:styled-content>i–<jats:styled-content style="fixed-case">T</jats:styled-content>i hand <jats:styled-content style="fixed-case">K</jats:styled-content>‐files did not produce microcracks at any levels inside the root canals.</jats:p></jats:sec>