Comparison of the Resistance of Teeth Instrumented with Different Nickel- XXXX Systems to Vertical Root Fracture: An In  Vitro Study.

@entity702 @entity1346 @entity174
INTRODUCTION: This study compared the @entity174 resistance of teeth instrumented with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (PTN, Dentsply Maillefer), WaveOne (Dentsply Maillefer), Twisted File (SybronEndo, Orange, CA), Mtwo (MT; VDW, M  nchen, Germany), and Revo-S (MicroMega, Besan  on, France) nickel- @entity702 systems and obturated with compatible gutta-percha cones of finishing files using the single-cone technique and a resin sealer. METHODS: The study included 72 mandibular premolar teeth. The roots were covered with additive @entity1346 and placed in Eppendorf tubes, which were filled with a self-curing acrylic. The tubes were separated into 6 groups: prepared with the ProTaper Universal (F4 40/.06) (group 1), prepared with the PTN (X4 40/.06) (group 2), prepared with the WaveOne reciprocating file (40/.08) (group 3), prepared with the Twisted File (40/.04) (group 4), prepared with the MT (40/.06) (group 5), and prepared with the Revo-S (AS 40/.06) (group 6). After the preparations were completed, all the teeth were filled with the appropriate gutta-percha systems. The force (N) was applied at a 1-mm/min crosshead speed until the roots fractured. Differences among the groups were analyzed by Tukey and analysis of variance tests. RESULTS: Group 2 was the most resistant to @entity174 , and group 5 was the least resistant. The difference in the @entity174 resistance between the 2 groups was statistically significant (P  =  .019). The resistance of group 3 and group 6 to vertical root @entity174 was similar, and the resistance of group 4 was slightly lower than that of the other groups (P  =  .058). CONCLUSIONS: The roots instrumented with the MT were the least resistant, and the roots instrumented with the PTN were the most resistant to VRF.
