Background: The purpose of this study was to evaluate the fracture strength of roots instrumented with the Wave one reciprocating file (Dentsply Maillefer, Ballaigues, Switzerland) and Hyflex CM (Coltene/Whaledentinc, Usa) and filled with the warm vertical compaction technique. Materials and Methods: In total, 60 mandibular premolar teeth were sectioned at or below the cementoenamel junction to obtain roots 13 mm in length. The roots were balanced with respect to buccolingualmesiodistal diameters and weight. They were distributed into 2 experimental groups and 1 control group (n = 20): no instrumentation (control group), instrumentation with Wave One with obturation, instrumentation with Hyflex CM with AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) was used along with single cone points. One week later, a vertical load was applied to the specimen’s canal until fracture occurred. Data were statistically analysed using 1-way analysis of variance (P=0.05). Results: The median fracture load was 415.74 N for the Waveone, median fracture load of 393.83N. However, the differences were not statistically significant (P=0.08). Conclusion: Instrumentation with the WaveOne and Hyflex CM system showed highest fracture resistance strength of standardized roots with respect to cross-sectional diameter and weight.

Fracture Strength, instrumentation, vertical root fracture, Wave One reciprocating file