Abstract : Purpose : The objective of this study was to determine the influence of the autoclave on the effect of controlled memory files of a martensite (M) Ni-Ti rotary file (NiTi-RF) and austenite (A) NiTi-RF.

 Methods : Two types of NiTi-RFs were selected : M-NiTi-RF (Hyflex EDM One File, n=10) and A-NiTi-RF (ProTaper Universal F2, n=10). Each file was prepared in a simulated artificial root canal. Pre-preparation, post-preparation and post-autoclave images of each file were recorded. Assessment of deformation of the files and their subsequent shape recovery was carried out visually and by comparing the digital images. The data was analyzed using Student's t-tests.

 Results : Visual assessment of files post-preparation revealed that M-NiTi-RF caused more ductile deformation than A-NiTi-RF. As a result of the measurement after autoclaving, M-NiTi-RF was unwound in shape more than A-NiTi-RF due to the shape memory effect.

 Conclusion : Post-preparation files became deformed as a result of use. However, M-NiTi-RF recovered in shape following autoclaving.