C-SHAPE RETREATMENT – Conical second molars can have some of the most variable anatomy in the adult dentition. Here we present two “c-shape” molar retreatment cases that highlight this unusual morphology. Due to the twisting, merging, splitting, and curving of these canals which are often all be joined by a thin slit of tissue called an isthmus, meticulous endodontics is essential in order to achieve healing.