Evaluation of dentinal micro-cracks caused by the ProTaper Universal, ProTaper Next and Reciproc rotary file systems used in root canal preparation

Aim: In this study, we compared the occurrence of dentinal micro-cracksafter use of the ProTaper Universal (Dentsply Maillefer, Ballaigues,Switzerland), ProTaper Next (Dentsply Maillefer), and Reciproc (VDW,Munich, Germany) nickel–titanium rotary file systems in root canalpreparation.Methodology: One hundred mandibular anterior teeth were divided intofive groups of 20 specimens each. Group 1 served as a control, with nointervention. In group 2, preparation was performed using the step-backtechnique and K files. In groups 3–5, root canal preparation was performedusing the ProTaper Universal, ProTaper Next, and Reciproc file systems,respectively. Following preparation, specimens were sectioned at 3, 6, and9 mm using a Minitom precision cut-off machine. The sections wereevaluated under a stereomicroscope. The following scoring system wasused to rate specimens: 1, no micro-crack; 2, incomplete micro-crack; and3, vertical root fracture. The results were statistically assessed (p≤0.05).Results: No micro-crack formation was observed in groups 1 and 2. Thehighest rate of micro-crack formation was observed in specimens preparedwith the ProTaper Universal file system (20%), followed by those preparedwith the Reciproc (11.7%) and ProTaper Next (6.7%) file systems. However,no significant difference was detected among groups (p>0.05). In thegroups ProTaper Universal and Reciproc files were used, 1 vertical rootfracture was found in 9 mm sections for each.Conclusions: Considering the limitations of in vitro studies, we canconclude that all rotary file systems used in this study led to dentinalmicro-crack formation in roots. The ProTaper Universal file system causedmore dentinal micro-cracking than did the ProTaper Next and Reciproc filesystems.