introduction: the aim of this study was to compare the formation of dentinal crack and craze lines in the root dentin during root canal preparation with three different niti endodontic systems, naming reciproc (rcp), protaper universal (ptu) and mtwo. methods and materials: one hundred extracted mandibular premolars with single canals were selected and decoronated. the teeth were randomly divid...

PURPOSE The aims of the present study were to compare the image quality and visibility of tooth cracks between conventional methods and swept-source optical coherence tomography (SS-OCT) and to develop an automatic detection technique for tooth cracks by SS-OCT imaging. METHODS We evaluated SS-OCT with a near-infrared wavelength centered at 1,310 nm over a spectral bandwidth of 100 nm at a ra...

Pluta polarizing interference microscope was used to follow the crazing that occur on the surface of stretched polypropylene fibres at different drawing conditions. The samples were stretched until crazing initiated, and then craze propagation was monitored as a function of drawing speed and test temperature. The effect of craze dimension on their propagation velocity was taken into account. Th...

In this study it is shown, for a commercial polystyrene grade, that the strain-rate dependence of craze initiation is equivalent to that of yielding. This implies that the kinetics of craze initiation are determined by the nonlinear flow behavior, and that the actual cavitation process is governed by an additional, apparently rateindependent, criterion. © 2004 Wiley Periodicals, Inc. J Polym Sc...