A comparison of the minimum canal wall thickness remaining following preparation using two nickel-titanium rotary...

To examine in vitro whether Profile or Hero 642 nickel-titanium rotary instrument systems substantially reduce the minimum canal wall thickness present following root-canal preparation.

The canal anatomy of 26 mesial roots from mandibular molars with separate buccal and lingual canals was evaluated before and after instrumentation using the Endodontic Cube. Following access, working lengths were determined and then samples invested within the cube using acrylic resin. Canal cross-sections were subsequently prepared. Samples were then instrumented within the cube and pre- and post-instrumentation images of the sections were compared to determine the minimum canal wall thickness remaining after preparation.

Buccal and lingual canals within the sections from each level (coronal to apical) showed a reduction in minimum canal wall thickness after instrumentation. No statistically significant differences in canal wall thickness were found between the two systems at any level of the root.

Instrumentation with either of the two systems under investigation did not compromise canal wall thickness. Pre-operative canal wall thickness was found to be the most significant factor determining the minimum canal wall thickness after preparation.