Assessment of Vertical Root Fracture Resistance of Endodontically Treated Teeth Instrumented by Single Endodontic Files

Root canal shaping procedures were performed. Irrigation was done after each three pecks of endodontic file. After instrumentation (Groups 1-3), the canals were dried with sterile paper points. The dentinal walls were then coated with Sealapex. For vertical root fracture resistance testing, sample preparation was done in acrylic blocks. Then roots were coated with polyvinylsiloxane impression material. After that roots were inserted again into acrylic resin blocks. The acrylic blocks with the vertically aligned roots were mounted in the Instron testing machine. 0.5 mm diameter round tip stainless-steel rod was fixed to the universal testing machine. The universal testing machine was adjusted and vertical compressive force was applied at a crosshead speed of 1mm/min. The Instron tester applied a slowly increasing force, until the root fractured. The maximum amount of force necessary to fracture every sample was recorded in Newton (N).