INFLUENCE OF TREATMENT MODALITIES OF NITI ROTARY FILES ON FLEXIBILITY AND CYCLIC FATIGUE RESISTANCE (IN VITRO STUDY)

Forty-eight (# 25) files were divided into two equal groups according to their type: Group I: Treated 2Shape (MicroMega SA, France). Group II: Non-treated ProTaper Universal (DENTSPLY Tulsa Dental Specialties, Tulsa, OK.) Groups were further divided into 2 subgroups according to the type of test conducted. Flexibility test was performed in subgroups I. A and II.A by means of a 3-point bending test (Fig 1) using a Universal Testing Machine. The load necessary to maintain a constant feed rate of (1min/mm) was recorded every 0.1 seconds with a specified maximum force of 10N. In subgroups, I.B and II.B cyclic fatigue resistance was tested using a custom-made dynamic device with a 60-degree stainless-steel artificial canal (Fig 2). Number of Cycles to Fracture (NCF) and Time to Fracture (TTF) were recorded. All data were tabulated and statistically analyzed using SPSS for Windows version 23.