C-shape canal is not very common system. Most often We can ring it in lower second molars. In this case " : " version is present. Only two canals have an anatomical apex (one located medially and one distally), but between them is long isthmus. Rotary files can shape only main canals, rest should be chemically disinfected. Ultrasonic activation of sodium hypochlorite and warm gutta percha obturation are essential for me in that kind of anatomy. What is your "tips and tricks" with C-shape?